Image source, Getty Images

As we've been reporting, Kharkiv officials say they have repelled a Russian attack, and are in charge of Ukraine's second city.

Here's a fuller translation of the statement from Kharkiv regional governor Oleh Synyehubov. The BBC has been told Kharkiv is under Ukrainian control, but we cannot verify his other claims.

"The control over Kharkiv is completely in our hands! Armed forces of Ukraine, the national police, the territorial defence forces are working: they are clearing the city of the enemy.

"The Russian enemy is completely demoralised. Right in the city, inside Kharkiv, a group of five to 10 people have surrendered to the Ukrainian army. As soon as they see at least one representative of the armed forces of Ukraine, they surrender.

"As for the situation in the wider region, here’s what is happening now: Chuhuiv [another city] is completely under control of the Ukrainian army, Ukrainian flags are hanged on the administrative buildings.

"The offensive of the Russian aggressor is ongoing in the following directions: from Lyptsi, Vovchansk, and Belhorod.

"We see separate regiments of [Russian] military vehicles. The armed forces of Ukraine are in their positions in active fighting."

Emma Vardy
Reporting from an RAF Voyager above Poland

We are in an RAF Voyager over Poland - about 50 miles from the Russian border - watching the UK’s Typhoon fighter jets refuelling in the air beside us.

British military jets have significantly stepped up their patrols since Russian forces invaded Ukraine, as part of the Nato mission to defend Europe - although the exercise is not related to President Putin's recent nuclear deterrent announcement.

The RAF Typhoons are effectively policing the skies in Poland and Romania to deter any further Russian aggression, demonstrating they have a strong presence here.

While these RAF jets are close to Russian airspace they are also able to gather information on the radar about what Russian military aircraft are in the air, and what they’re doing.

If there was to be a Russian military incursion into a Nato country, these fighter jets may be cleared to engage them.

But for now it’s hoped the increased presence of Nato forces in the air will send a clear message to Moscow.

Wing Commander Mike Udall tells me: "It’s partly reassurance to show Nato allies we’re there with them, to maintain integrity of the airspace, make sure we’ve got a good understanding of who’s flying where and to react to any emerging threats.

"There’s a very human element to is and we all feel that, we all watch the news, but our role is to be there and do our own job and contribute in the way we can."

The US has responded to President Putin's order putting Russia's nuclear forces on a "special" state of alert.

The move makes it easier to launch weapons - but our security correspondent Gordon Corera said it was a way for Russia to send a warning to Nato, rather than signalling an intent to use them.

The US Ambassador to the United Nations, Linda Thomas-Greenfield, called the move "unacceptable" in an interview with CBS News.

"It means that President Putin is continuing to escalate this war in a manner that is totally unacceptable and we have to continue to stem his actions in the strongest possible way," she said.

Ukrainian president Volodymyr Zelensky has released a statement following his conversation with Belarusian leader Alexander Lukashenko earlier today.

“We agreed that the Ukrainian delegation would meet with the Russian delegation without preconditions on the Ukrainian-Belarusian border, near the Pripyat River," it read.

“Alexander Lukashenko has taken responsibility for ensuring that all planes, helicopters and missiles stationed on Belarusian territory remain on the ground during the Ukrainian delegation's travel, talks and return.”

Zelensky had earlier said he would not meet a Russian delegation on Belarusian territory because Russia's invasion was launched in part from Belarus.

Neither Russia nor Belarus have issued any statements about potential talks.

Gordon Corera
Security correspondent, BBC News

President Putin has ordered his military command to put nuclear forces on a "special" state of alert.

This is after what Moscow calls "aggressive statements" by Nato countries.

Russia's leader had already issued a coded warning that he was willing to use nuclear weapons as he began his invasion of Ukraine.

Last week, he warned that "whoever tries to hinder us" would see consequences "you have never seen in your history".

These words were widely interpreted as signalling a threat to use nuclear weapons if the West stood in his way.

The very public shift to high alert status is a way for Moscow to send a warning. Moving to alert status is likely to make it easier to launch weapons more quickly. But it does not mean there is a current intent to use them.

Russia has the largest stockpile of nuclear weapons in the world but also knows that Nato also has enough to destroy Russia if they were used.

But the aim is likely to try and deter Nato support for Ukraine by creating fears over how far he is willing to go and creating ambiguity over what kind of support for Ukraine he will consider to be too much.

Russian President Vladimir Putin has ordered the Russian military to put its nuclear forces on "special alert" - the highest level of alert for Russia's Strategic Missile Forces.

Speaking to top military officials, including Defence Minister Sergei Shoigu, he said Western nations had taken "unfriendly actions" towards Russia and imposed "illegitimate sanctions".

We'll bring you an assessment of this move shortly.

Viktoriia Zhuhan
BBC Ukrainian

Here's some more of what we're hearing from civilians on the ground in Kharkiv.

One 34-year-old woman said she spent last night in the basement of her apartment block with around 35 others.

"We were lucky last night. A blast hit the road next to our block but it didn’t hit our block," she said.

"Later, we found out that two pedestrians had been killed and another wounded. The wave of the blast was so strong that my ears popped [like when you land in a plane] even though I was sitting in the basement.

"Just before the blast our neighbour down in the basement was instructing their two young kids aged three or four what to do if there was an explosion.

"Listening to this was horrific, my hairs were standing on end at the thought that three-year-old children were having to be taught what to do during shelling.

"Throughout the night one young girl kept waking up her mum. She’d sit up crying screaming: 'Mom, I’m scared, please save me, save me now.'

"She only calmed down by the morning after her mum had sat holding her all through the night."

She said that, even though Ukrainian forces now control Kharkiv, she continues to hear blasts and that the offensive against the city appears to be ongoing.

"The reserve army volunteers are doing a great job," she said.

"I’m glued to my phone but when the connection goes down I get a little panicky, because then I don’t know how my loved ones and friends are getting on in other parts of the city.

"Every hour I look outside [above ground] to connect to the phone network and internet and call them, though it’s a risky thing to do. The tension here is horrible, but so far we are all holding on.”

A video posted on social media appears to show defiant Ukrainians chanting and putting sand into bags to create road blocks.

"I've never seen such unity before. Everyone's loading, everyone's doing their best. Lots of bags. Glory to Ukraine,” a man can be heard saying.

The crowd responds by chanting: "Glory to heroes!" and "Glory to our nation!"

The BBC was unable to independently verify the footage, which was said to have been filmed in Kryvyi Rih - President Volodymyr Zelensky’s hometown.

Image source, GETT

As Germany announces a huge increase in defence spending (see below and 11:04 GMT post) German police say more than 100,000 people are taking part in a protest against the Russian invasion in Berlin.

Demonstrators have filled a large area between the Brandenburg Gate and the Victory Column / Siegessäule and more people are arriving all the time. They say the crowd could end up reaching Alexanderplatz, three kilometres away.

Earlier this week, Germany also confirmed it would be sending 1,000 anti-tank weapons and 500 Stinger missiles to Ukraine.

Image source, Reuters

Image source, Reuters

Image source, Reuters

Liz Truss reacts to the earlier news that Germany will now meet the Nato defence spend target, which is 2% of national GDP...

Viktoriia Zhuhan
BBC Ukrainian

And here's more from the civilians we've spoken to on the ground in Kharkiv, where Ukrainian forces have repelled a Russian attack.

One university professor in his fifties said there were tanks fighting only a few kilometres from his home and that some of the street fighting was even closer.

"We are staying in our house with a cellar," he said.

"It’s my wife and me, two sons, and my 80-year-old mom. We keep the boys in the cellar most of the time.

"We have electricity, warm home, water, and connectivity.

"Not everyone is this lucky. We called our friend to join us – she has a new-born and a toddler. But she can’t take a risk to try and get to us through the whole town."

He said he's ethnically Russian and that Russian is his first language but that he is in the process of learning Ukrainian.

"I feel this is the right thing to do," he said.

"I started two or three years ago to use it at work, and recently started speaking Ukrainian in private conversations."

He added that he also believed that Ukrainian forces have regained full control of Kharkiv - as the city's governor has claimed.

"Even the groups that entered the city were killed or destroyed as far as I know," he said.

"Even when they were here, they just did a breakthrough, they didn’t control the city.”

Viktoriia Zhuhan
BBC Ukrainian

The BBC has been speaking to civilians on the ground in Kharkiv after Ukrainian forces claimed to be back in control of the city.

One woman, a 30-year-old who did not want to be named, spoke about being in the city as Russian forces moved in overnight.

“I can’t describe the sounds that woke us up at 00:30 last night," she said.

"It’s something like Star Wars above your head. It lasted about 15 minutes with no breaks."

She continued: “We have taken shelter at our friend's house. I can't tell you where because it’s too dangerous to do so.

"We fled here because our flat was in a tower block near to the Kharkiv ring road [closer to where Russians troops entered the city]. So now we’re further away from the most dangerous zone.

"I can still hear the sounds of shooting but it’s not as intense as it was yesterday. But we all start to feel hopeless again whenever we hear more horrible news.

"Just recently [Belarusian leader Alexander] Lukashenko suggested using nuclear arms – how are we supposed to be feeling?”

As we just reported, the mayor of Kyiv says there are no Russian troops in the capital - and that "saboteurs" have been "detected and neutralised".

But the city is a long way from normal. There is a curfew until Monday, and residents have taped their windows in case gunfire or explosions break the glass.

This picture is from Oleksander Dzenhilevsky in Obolon in the north of Kyiv.

Image source, Oleksander Dzenhilevsky

Image source, AFP

The mayor of Ukraine’s capital Kyiv has said there are no Russian troops in the city, as it continues to defend itself from attacks.

Vitali Klitschko said that “military, law enforcement and territorial defence” officials were continuing to “detect and neutralise saboteurs”.

As we reported earlier, people living in Kyiv are under orders to stay indoors until Monday, with warnings from authorities that anyone venturing out "will be considered members of sabotage groups of the enemy".

BBC producer Kathy Long said Sunday dawned cold and quiet in Kyiv, with police, the military and armed volunteers the only people visible on the streets.

In the message on his Telegram channel on Sunday, Klitschko said that since the start of Russia’s invasion, nine civilians had been “lost or killed” in Kyiv, including one child.

Russian forces have reportedly been in the outskirts of the city since Friday, with shelling and gunfire heard across Kyiv.

Image source, gett

Ukrainian President Volodymyr Zelensky has said he has spoken with Belarus leader Alexander Lukashenko, but didn't give any details of what was discussed.

As we reported earlier (see 08:02 GMT post), Russia said a delegation had arrived in Belarus - ostensibly for talks with Ukraine.

But Mr Zelensky rejected the offer saying talks in Minsk could have been possible if Russia had not attacked Ukraine from Belarusian territory.

But he said he remained open to negotiations in other locations.

Liz Truss was speaking to Sophie Raworth on the BBC this morning...

Image source, Getty Images

Pope Francis has called for an end to the conflict in Ukraine.

Speaking to an audience in St Peter's Square, he said: "Let the weapons fall silent. God is with those who seek peace, not those resorting to violence."

He has also called for humanitarian corridors to help refugees out of Ukraine.

And he condemned those who "trust in the diabolic and perverse logic of weapons".

As we've been reporting, Ukraine claims to be back in control of Kharkiv - its second city - on day four of the full-scale Russian invasion.

The Russians launched their attack on Thursday from the north towards Kyiv, from the east towards Kharkiv, Sumy, Donetsk and Luhansk, and from Crimea in the south.

Dozens of targets have been struck, as Russian troops have poured into Ukraine and launched missile strikes on major cities.

If you're struggling with the geography of all this, we've collated the key movements in a series of maps.

Ukrainian forces have regained control of the key city of Kharkiv, the regional governor has said.

In a post on Telegram, Oleh Synyehubov said: "Control over Kharkiv is completely ours!

"The armed forces, the police, and the defence forces are working, and the city is being completely cleansed of the enemy."

Russian troops were able to enter the city, Ukraine's second largest, overnight.

Footage circulated on social media showed street fighting between Ukrainian and Russian troops.

The situation on the ground remains fluid and claims of control are hard to verify - but civilians on the ground have also told the BBC that Kharkiv is back under Ukrainian control and that conflict on the streets is easing.