And here we come to the end of today's live coverage. Here's a reminder of the day's key developments:

• Ukraine's President Volodymyr Zelensky has made a rare visit outside of the nation's capital to Kharkiv, where he met troops on the front line
• The Russian ambassador to the UK Andrei Kelin tells the BBC his country will not use nuclear weapons in Ukraine
• He shies away from addressing questions about CCTV footage of Moscow's soldiers committing alleged war crimes
• Russian forces continue their assault in eastern Ukraine with a number of assaults around Severodonetsk - the largest city still held by Ukraine in the eastern Donbas region
• The governor of the Luhansk region accuses Russia of systematically destroying Severodonetsk and claims more civilians have been killed there

Image source, Russian Defence Ministry

Russia is reported to have fired its latest multiple-rocket system against Ukrainian targets in the Kharkiv area – a weapon described as a giant flamethrower.

That is what a Russian security official told the state-run Tass news agency. It has not been confirmed officially.

The TOS-2 Tosochka is a thermobaric fuel-air weapon: it creates massive explosions by igniting gas clouds on impact, depriving anyone in the area of oxygen.

Ukraine has pushed Russian forces back from the outskirts of Kharkiv, the second city, which was visited by President Volodymyr Zelensky on Sunday.

Earlier Russia confirmed that it was using TOS-1 Solntsepyok (“Blazing Sun”) rockets against targets in the Donbas, where Ukrainian forces are under constant, intense bombardment.

TOS-1 is also thermobaric, with a range of up to 10km (six miles). The TOS-2’s manufacturer Rostec says TOS-2 has a longer range, better automatic targeting and more versatility. TOS-2 rockets are carried on an armoured truck, not a tank chassis.

Image source, Russian Defence Ministry

Hugo Bachega
Reporting from Zaporizhzhia

Image source, EPA

It was a rare trip for President Zelensky outside Kyiv. He visited troops on the frontline near Kharkiv, Ukraine’s second city, handed out awards and gifts, and thanked soldiers for their service.

“You’re risking your life for all of us and our state,” he said. “Thank you for defending Ukraine’s independence. Take care!”

The visit was a demonstration of the country’s success in pushing Russian forces back from the city. And was probably intended to boost morale as Ukraine tries to contain a massive Russian offensive in the Donbas area further east.

An onslaught that is causing enormous suffering and destruction.

Hours after the president left, loud explosions were reported in Kharkiv. A message that the threat posed by the invading forces there may have subsided, but it’s not entirely gone.

James Waterhouse
Kyiv correspondent, BBC News

Ukraine’s capital is 1,540 years old this weekend, and you’d be forgiven for assuming Kyiv wasn’t in the mood to celebrate.

After all, it’s just over three months ago that the city found itself surrounded by Russian forces, with some predicting it would fall within 72 hours.

At the time, I remember standing outside the Opera House, where the only gathering of people was outside a nearby pharmacy - scared and angry.

Today it's a different scene. There is a sea of smiling faces, colourful outfits and cheerful chatter as people walk in to watch a performance of Verdi's Rigoletto. Shows returned last week; and you can’t help but feel the joy of those lucky enough to get a ticket. Tickets are limited to 300, the capacity of the theatre's bomb shelter.

“Life really goes on and we do not stop,” says Pavlo, one of the soldiers in uniform, in passing. “We hope for the best and believe everything is going to be alright”.

Backstage one of the lead singers, Olga Fomichova, sits illuminated by her make up mirror. “I can see our audience needs us, from the sold-out tickets, but it won’t be the same” she admits.

“I don’t have anger or defiance, only the desire to be heard, that the Ukrainians are a cultural and educated nation which deserves world-wide respect and attention.”

For several of its 1,540 years, other rulers and empires have tried to take Kyiv by force. Some have been more successful than others, but few predicted such attempts would be made in 2022.

Joe Inwood
BBC News, Kyiv

Image source, Ukraine President's Office

Volodymyr Zelensky has not turned out to be the president many predicted. The former comedian, the voice of Ukrainian Paddington Bear, was once mocked as a lightweight.

Now, he is compared to Winston Churchill.

His steadfastness in the face of overwhelming Russian force is credited by many as being a crucial factor in his country’s remarkable performance in the beginning of this war.

His defiant videos from the streets of the capital, Kyiv, were a metaphorical middle finger to Russia and its president.

While President Zelensky would appear with his colleagues, arms around their shoulders, Vladimir Putin was pictured at one end of an almost comedically long table, his officials barely in shouting distance.

As effective as they were, however, those appearances were all in the capital. Today’s visit to Kharkiv is the first time he has left the Kyiv region since the start of Russia’s invasion.

He met the troops that have not just defended Kharkiv, but repelled the Russians, almost pushing them back to the international border.

The fact that he was able to visit shows just how much the tide has turned in Ukraine’s second city. A few weeks ago, this morale boosting visit would never have been possible.

But, do not be mistaken, Kharkiv is only safe for now. Elsewhere, Ukraine very much appears on the back foot, withering Russian artillery barrages forcing them to retreat in the Donbas.

With its charismatic president, Ukraine has very much won the informational war. Unfortunately for them, that is not where this conflict will ultimately be decided.

Image source, EPA

Image source, Reuters

Stopping Russia is the common mission of all civilised countries, Ukrainian presidential adviser Mykhaylo Podolyak has said.

"'Why does the world pay more attention to Ukraine than to Africa or the East?' - such a narrative is promoted by Russian agents," he wrote in a tweet.

The Ukraine war is not a local conflict - it is the question of what the world will be like tomorrow, he added.

Allowing Russia to win would "open Pandora's box and push humanity into the dark ages."

Podolyak went on to say: "Any autocrat would be able to provoke territorial conflicts, seize countries and exterminate nations.

"Stopping Russia is a mission of all civilized countries. There's time, but we should hurry up."

Image source, Getty Images

Moscow-imposed authorities in the southern city of Kherson say nearby fighting could affect the timing of its formal bid to join Russia.

Russian forces occupied Kherson in early March - one week after the invasion of Ukraine began. It was the first major city to fall.

Kirill Stremousov, deputy-head of Kherson's Moscow-installed administration, says the process might involve a referendum, backtracking on previous comments suggesting none was needed.

According to Reuters news agency, he says: "We'll announce later when some kind of vote or plebiscite is planned, but it won’t be today and it won’t be tomorrow because our first task is to restore order in the Kherson region."

Russia has said that the fate of the Kherson region is for local residents to decide.

But the UK Ministry of Defence said, in an intelligence update in April, external, a referendum would be a way for Russia to justify its occupation of Ukraine.

And President Zelensky has said it fits in with Russia's plans of breaking Ukraine apart by creating "pseudo-republics" throughout the country.

He has advised people not to give the Russian authorities any personal data, such as passport numbers, as they might be used to falsify votes.

More now on President Zelensky's rare trip outside of the capital Kyiv.

He visited the frontline in the Kharkiv region where he spoke with troops and presented gifts.

It comes as intense fighting continues in the region as troops attempt to regain control of the area from the Russians.

Here are some more pictures of his visit.

Image source, Ukraine President's Office

Image source, President of Ukraine's office

Image source, President of Ukraine's office

Image source, President of Ukraine's office

Image source, President of Ukraine's office

Ukraine's president has made a rare trip outside the capital, Kyiv, the presidential office says.

Mr Zelensky visited front line positions in the Kharkiv region, it said.

"I want to thank each of you for your service. You risk your life for all of us and our state," the president told troops.

The north-easten city has seen some of the worst fighting since Russia launched its invasion of Ukraine on 24 February.

Image source, Ukraine president's office

Turkey's President Recep Tayyip Erdogan has said last week's talks with Finnish and Swedish delegations were not at the "expected level" and Ankara cannot approve their applications to join the Nato military alliance.

"For as long as Tayyip Erdogan is the head of the Republic of Turkey, we definitely cannot say 'yes' to countries which support terrorism entering Nato," the president said.

Without the support of all Nato members, Sweden and Finland cannot join the military alliance.

Both Nordic countries deny supporting Kurdish militants. But they have joined other EU countries in imposing a weapons embargo on Turkey following its operations against Kurdish groups in Syria.

What is Nato and how can Finland and Sweden join?

If you're just joining us, here is a brief recap of the latest events in Ukraine to bring you up to speed. Russia's ambassador to the UK says his country will not use nuclear weapons in Ukraine

• Russian ambassador to the UK Andrei Kelin tells the BBC he does not believe Russia will use tactical nuclear weapons in its invasion of Ukraine
• He claims Russia's leaders never said they would like to seize Kyiv and says that he didn't think it was possible to capture the Ukrainian capital
• He shies away from addressing questions on CCTV footage of Moscow's soldiers committing alleged war crimes in Ukraine
• He accepts the besieged city of Mariupol has been destroyed by fighting and criticises UK Foreign Secretary Liz Truss, calling her "very belligerent"

Russian forces continue assault in eastern Ukraine

• Russian forces launch a number of assaults around Severodonetsk - the largest city still held by Ukraine in the eastern Donbas region
• The governor of the Luhansk region accuses Russia of systematically destroying Severodonetsk and claims more civilians have been killed in the city
• Ukraine's President Volodymyr Zelensky said the situation remains difficult in the Donbas and Kharkiv regions where he said Russia was trying to "squeeze out some result for itself"

As we reported earlier, Russia's defence ministry says its missiles have destroyed a large arsenal of Ukrainian army weapons in Kryvyi Rih - the home city of Ukrainian President Volodymyr Zelensky.

Now we can bring you more details. Ministry spokesman Igor Konashenkov claims in the last 24 hours more than 300 "nationalists" [Ukrainian soldiers] have been killed.

He also claims a number of other Ukrainian military targets were hit in the offensive, including a Russian defence systems shooting down a Ukrainian SU-25 fighter jet in Dnipro.

He says: "In total, as a result of Russian air strikes, more than 300 nationalists and up to 50 units of military and special equipment of the armed forces of Ukraine were destroyed."

The governor of the Luhansk region has accused Russia of systematically destroying the city of Severodonetsk and its residents.

Serhiy Haidai said the attacks were relentless as fierce fighting rages in the area.

Severodonetsk is the easternmost place in the Donbas region still held by Ukraine and it is currently a key target for Russian forces.

The Luhansk governor said more civilians in the city had been killed in the latest attacks and buildings had been destroyed, including apartment blocks and a cinema.

But he said Russian troops trying to capture a vital road out had been driven back.

Earlier Ukraine's President Volodymyr Zelensky said the situation remained difficult in the Donbas and Kharkiv regions where he said Russia was trying to "squeeze out some result for itself".

Image source, .

Russia's defence ministry says that missiles have destroyed a large arsenal of the Ukrainian army in Kryvyi Rih, Ukrainian President Volodymyr Zelensky's home city, state news agency Tass reports.

The defence ministry also said Russian anti-aircraft defence systems shot down a Ukrainian SU-25 fighter jet in Dnipro.

Steve Rosenberg
BBC Russia editor

Image source, PA Media

What we heard from Russia's UK ambassador Andrei Kelin, we’ve been hearing for years from Russian officials whenever their county is accused of anything.

All accusations are rebuffed, all evidence of Russian complicity is dismissed.

What you end up with is this parallel reality in which CCTV footage of Russian soldiers shooting dead unarmed Ukrainian civilians is dismissed as a joke or a computer game.

Where the horrors of Bucha are dismissed as a fabrication, and where the levelling of residential areas of Mariupol is brushed aside as either collateral damage or blamed on Ukrainian soldiers.

In other words, none of this is ever Russia’s fault, everyone is against Russia, everyone is blaming Russia, everyone is accusing Russia and it claims it is the innocent party.

This is the Kremlin narrative which we’ve heard many times before. We heard it after the Salisbury poisonings, we heard it after the attempted assassination of the Russian opposition leader Alexei Navalny and we’re hearing it again now.

As we've previously reported, Russia's ambassador to the UK has told the BBC he does not believe his country will use tactical nuclear weapons in the war against Ukraine.

He has also criticised the UK's Foreign Secretary Liz Truss for her tough stance on Russia. Britain has imposed a number of sanctions on Russian individuals and businesses, as well as sending weapons to Ukraine.

Ambassador Andrei Kelin told the BBC's Clive Myrie: "She's neither a professional military man or she's not for a long time at this position.

"But she's very belligerent...

"On the position that UK would like to supply more and more arms, [but] not to think about the future of Ukraine or of Europe...

"But just to instigate conflict. Why this? What's the motivation for that?

"To make Russia more feeble?"

The ambassador added that Russia's economy has not "toppled down" despite the restrictions and asked what the benefit of sanctions was for the UK, which has seen inflation hit a 40-year high, partly driven by the Ukraine war.

After sanctions were imposed on Russia, the rouble fell 22% in value pushing up the price of imported goods, before it recovered.

More than 1,000 international companies have also suspended trading in Russia or withdrawn altogether - including McDonalds, Coca-Cola and Starbucks.

Jeremy Bowen
Reporting from Donbas

Image source, Getty Images

The question about negotiating in a war depends on the battlefield and on the state of mind of the parties contesting it.

It has to get to a point where either side is suffering so much they are prepared to go into negotiations and give some ground, or that one side feels it has achieved enough and it is prepared to bank those gains.

But at the moment I think both the Russians and Ukrainians have unfinished agendas.

The Ukrainians want the Russians out. The Russians want to move forward and make their points, and deliver a victory.

So I think politically there is no chance right now for a negotiation that means anything other than people getting together and talking in a room.

Russia has rejected accusations that its invasion of Ukraine has created serious threats to global food security, instead blaming Western sanctions.

The West has accused the Russian military of holding food supplies hostage for millions around the world.

The war in Ukraine has blocked the country's main ports on the Black sea, severely impacting food supply chains around the world. Ukraine is a major exporter of wheat, but now millions of tonnes of grain are stuck - impacting the countries that can least afford it.

"The attempts of the West to attribute all troubles to the special military operation and accuse Russia of blocking foreign ships in the ports of the Black Sea and the Sea of Azov are absolutely groundless," Foreign Ministry spokeswoman Maria Zakharova said.

"The main catalyst for the existing negative trends was the anti-Russian sanctions of the West, which led to a rupture of ties in the field of global logistics and transport infrastructure," she said.

The hike in prices for agricultural products started in 2020 "and is by no means a result of the special military operation" in Ukraine she claimed, before also blaming Covid.

The pandemic "has severely disrupted value chains and significantly increased the cost of food transportation services", she added.

James Waterhouse
Kyiv correspondent, BBC News

Image source, Getty Images

The war is especially raging in the east of Ukraine in the Donbas region.

Russian forces have launched a number of assaults around the city of Severodonetsk, which is increasingly finding itself surrounded.

Military experts think there is not much for Russia to gain economically or militarily by taking the city other than to declare some kind of early victory in the war, as it remains the last major city not in Russian control in the region of Luhansk.

What isn't clear is whether Russian President Vladimir Putin, should the Donbas region fall, will continue to try and take more of Ukraine.

It's been another night where we've seen more missile attacks, which continually raise questions over what happens next.

Image source, .

Russia’s ambassador to the UK has told the BBC he does not believe his country will use tactical nuclear weapons in the war against Ukraine.

Speaking to Clive Myrie, Andrei Kelin said such weapons would be used only if Russia’s existence was threatened.

The ambassador also denied Russian forces were shelling civilians, and said allegations of war crimes in the town of Bucha were a "fabrication".

Kelin's claims are contradicted by numerous eyewitness accounts from residents, who have told the BBC that Russian troops executed their loved ones.

The full interview can be seen in the UK on the Sunday Morning programme, BBC One 9am.