Please join us here for updates and analysis over the weekend.

We're closing our live coverage of the war in Ukraine for today in a little while.

We'll leave you with a brief recap of what's happened:

Fighting in the east

• The Russian air force has attacked an arms depot in the Kharkiv region in Ukraine, state news agency RIA reports
• UK military intelligence says an entire Russian battalion was wiped out during a thwarted effort to establish a bridge over the Siversky Donets river in the eastern Donbas region
• The governor of the Luhansk region says his forces stopped three Russian efforts to lay down bridges on different days

Beyond the Donbas region

• Ukraine's defence minister has said he hopes to arm a million fighters as the country prepares for a "new, long phase of war"
• A Russian serviceman accused of killing an unarmed Ukrainian civilian has appeared in court in Kyiv - ahead of the conflict's first trial of a soldier accused of war crimes
• Ukraine says 1.2 million people - including 200,000 children - have been deported from their country against their will since the fighting started - but the BBC's not been able to verify this

In diplomacy

• The defence ministers of Russia and the US have spoken for the first time since Russia began its invasion - with the American side calling for an immediate ceasefire
• The leaders of Finland and Sweden have spoken to US President Joe Biden about their plans to join Nato, but Turkey's President Erdogan has said he was against them joining
• The breakaway region of South Ossetia in Georgia announced plans for a referendum on joining Russia
• Electricity exports from Russia to Finland are being suspended from Saturday

You can read about more of the day's key events here.

Image source, Reuters

Ukraine has said it is returning the bodies of fallen Russian troops back home.

On Friday, military officials were seen loading and stacking bodies collected from the Kyiv and Chernihiv regions onto refrigerated rail cars.

The move is in accordance with "the norms of international humanitarian law", according to Volodymyr Lyamzin, the head of Ukraine's civil-military cooperation.

"After the active phase of the conflict is over, sides have to return the bodies of the military of another country. Ukraine is ready to return the bodies to the aggressor,” Lyamzin told the Reuters news agency.

Several refrigerated trains have reportedly been stationed in other parts of the country as well.

Ukraine claims it has killed some 20,000 Russian troops. Russia has not updated its death toll since 25 March, when it acknowledged 1,351 deaths.

The BBC Ukrainian service is reporting that the Ukrainian army has released two decks of cards depicting Russians they suspect of war crimes.

The idea replicates the set of 55 playing cards that the US military produced in the 2003 invasion of Iraq, depicting what it said were the most wanted members of Saddam Hussein's government.

Commander-in-Chief of the Armed Forces of Ukraine, Valerii Zaluzhnyi, said the cards were produced with the help of volunteers from the international intelligence community InformNapalm.

US President Joe Biden has spoken with the leaders of Finland and Sweden about their plans to join the Nato alliance.

The White House said Biden had held a joint phone call with Finnish President Sauli Niinistö and Swedish Prime Minister Magdalena Andersson about the issue on Friday.

A readout of the call claims the trio discussed Nato’s Open Door policy and "the right of Finland and Sweden to decide their own future, foreign policy, and security arrangements".

Afterwards, Niinistö wrote on Twitter that he "went through Finland's next steps towards Nato membership" on the call.

It comes a day after Niinistö and Finland's PM Sanna Marin called for the historically neutral country to apply for Nato membership "without delay".

Sweden will announce its own decision on joining Nato on Sunday.

As we reported on Thursday, a US lawmaker has single-handedly blocked a multi billion-dollar aid package to Ukraine from passing this week.

President Joe Biden had called on Congress to send the bill - $39.8bn in economic, humanitarian and security assistance - to his desk by the end of the week, but Senator Rand Paul blocked an expedited vote on Thursday evening alleging that the government was "shuffling money out the door as fast as they can" with no oversight.

"My oath of office is to the US Constitution, not to any foreign nation," Paul said on the Senate floor defending his decision. "We cannot save Ukraine by dooming the US economy."

The senator from Kentucky is calling for a watchdog provision in the bill to oversee how the money is being spent, an amendment that would require further delays in the bill's passage.

Congressional leaders have chided the congressman for causing the delay, as the current bill has enough votes to pass in the Senate through regular order but this will now not happen until next week.

Paul's defiance has been lauded in some corners, with former president Donald Trump's son arguing lawmakers in Washington - or "the swamp" as he called them - "don't want transparency".

Image source, Getty Images

Sweden and Finland have said that they will hold talks with the Turkish government after its president, Recep Tayyip Erdogan, said he was not in favour of their plans to join Nato.

The Swedish and Finnish foreign ministers, Ann Linde and Pekka Haavisto said they would speak to their Turkish counterpart, Mevlut Cavusoglu, about the issue at a Nato meeting on Saturday.

Erdogan said that Nordic countries had given asylum to people Turkey considers to be Kurdish terrorists.

He added that he did not want Nato to repeat what he called the mistake of the past when it allowed Greece to join.

Responding to Turkey's comments, the US said Turkey "is a valued Nato ally" and "they've been involved and helpful in trying to get a dialogue going here, between Russia and Ukraine".

John Kirby, press secretary for the US Ministry of Defence, added "we're working to better clarify the [Turkey's] position here".

Image source, Reuters

Law enforcement officers in Ukraine are investigating 41 Russian servicemen suspected of having committed war crimes in the country, Interfax-Ukraine news agency reports.

Prosecutor-General Iryna Venediktova said the suspects will be investigated for a range of crimes - from the bombing of civilian infrastructure, killing of civilians, rape and looting.

The suspects will answer before a Ukrainian court of law, she added.

Today, a Russian soldier accused of killing an unarmed 62-year-old civilian appeared in court in Kyiv.

Vadim Shishimarin, 21, was brought to court for a preliminary hearing. He faces possible life imprisonment on charges of war crimes and premeditated murder.

During a televised address on Friday evening, Venediktova said preliminary hearings on two more suspects will be carried out next week.

The leader of breakaway region South Ossetia has announced a referendum on whether to become a part of Russia.

A statement from the office of Anatoly Bibilov said it was his people's "historic aspiration" to come together with Russia, and the vote would take place on 17 July.

Moscow recognises the region as independent, after a brief war between Russia and Georgia in 2008, and has provided financial support, Russian citizenship for its citizens and sited military bases there.

Georgia maintains that South Ossetia is an occupied territory and previously said that a referendum on joining Russia would be unacceptable.

Negotiations with Russia over freeing the Ukrainian fighters under siege in the Azovstal steel plant in Mariupol were "very difficult", Ukraine's deputy prime minister has said.

In an online post, Iryna Vereshchuk wrote: "The result may not be to everyone's liking, but our task is to evacuate our boys. All of them.

"Alive."

Yesterday, the Ukrainian government said that it was pushing for safe passage for 38 badly wounded fighters, in exchange for captured Russians.

The Azovstal complex once sheltered hundreds of civilians and fighters, but after several weeks trapped underground civilians were freed in a series of humanitarian convoys last week and negotiations over the fighters began.

The Russian air force has attacked an arms depot in the Kharkiv region in Ukraine, state news agency RIA reports.

The news agency quoted the Russian defence ministry saying it had hit the facility on Friday.

Meanwhile, eyewitnesses to an earlier attack in Kharkiv told news agency AFP that they had been targeted by a Russian tank as they tried to seek shelter at home.

"Four people died, two were injured. My daughter died from a shrapnel wound in the back of her head," Olga Karpenko, 52, said.

The BBC has not been able to independently verify this information.

Image source, Reuters

More details have emerged of the telephone call between US Defence Secretary Lloyd Austin and Russia's Defence Minister Sergei Shoygu, in which General Austin called for an immediate ceasefire.

Pentagon spokesman John Kirby said that Gen Austin had stressed the importance of maintaining communication, after Moscow had appeared uninterested in speaking to the US on previous attempts to hold the conversation.

An anonymous US official said the tone of the hour-long call was "professional", but did not resolve any specific issues or lead to changes in Russian policy, news agency Reuters report.

Russia's defence ministry confirmed that the US had initiated the call, and discussed "topical issues of international security... including the situation in Ukraine".

Olga Ivshina
Senior correspondent, BBC News Russian

Image source, AFP

Since the start of the war, our team has been following and verifying reports of losses among Russian troops fighting in Ukraine by following official announcements, local media reports as well as social media and speaking to the relatives of Russian servicemen.

Up to this moment BBC News Russian has been able to verify the deaths of 2,336 Russian servicemen. We have been able to establish their names, ranks and military units where they served.

This is nearly twice the latest official figure released by the Russian Defence Ministry in March.

It is likely that the real figure of the Russian military in Ukraine is far higher than we have been able to establish. But our data analysis helps to see the trends of what is happening with the Russian army fighting in Ukraine.

Nearly 20% of all confirmed military casualties are officers. This proportion has remained unchanged for the past three months. Experts say that Russian officers may have to risk more on the frontline because of persistent problems with communications.

Over 25% of all losses are paratroopers and marines. These units are often used in reconnaissance and storming operations. However they often don’t get enough operational support and evacuation opportunities for the wounded.

Most of the casualties, confirmed by us, came from the least developed and economically deprived regions of Russia. There are only three confirmed deaths of servicemen from Moscow, even though the capital makes up almost 9% of the Russian population.

Ukrainian authorities now say that nearly 27,000 Russian soldiers have been killed.

Read the full story on the BBC's Russian service here.

Image source, Reuters

As we've been reporting, Ukraine's Defence Minister Oleksiy Reznikov has said the country is entering a new stage of the war.

Reznikov pledged to arm a million fighters using the new weapons and military equipment the US and other Western countries have been donating to the country over the last couple of weeks.

The defence minister said that during the beginning of the war, "volunteers were extremely helpful" and it's thanks to their mobility that they "quickly resolved highly pressing issues".

Reznikov said that to win, Ukraine "must plan resources carefully and avoid mistakes" and was investing in Ukrainian production facilities to "ensure the stability and frequency of deliveries".

In his statement on Facebook, he said that Ukraine had relied on charitable aid from citizens, volunteers, and civic organisations for a significant proportion of its military equipment.

He said that at the end of April, Ukraine's ministry of defence was relying on donations for 50% of the bullet proof vests used in combat.

But as of 13 May, Ukraine has managed to increase its production to provide 57% of the armed forces' bullet proof vests, he added.

More now on the suspension of electricity exports from Russia to Finland, which followed rising tensions over Helsinki's announcement of its plan to join Nato.

RAO Nordic, a subsidiary of the Russian company Inter RAO, said non-payment was behind its decision to halt electrity supplies.

The company said they had not received funds since 6 May and described the situation as "exceptional", adding that it is the first time it's happened "in over 20 years of our trading history".

It did not specify whether this was due to the impact of sanctions but added, "we hope that the situation will get improved soon and the electricity trade with Russia could resume".

Meanwhlle, the Finnish grid operator Fingrid said it did not anticpate any problems with supply as a result of the suspension.

It said it would make up the shortfall by generating more power domestically and increasing imports from Sweden.

If you're just joining us, here's a little recap of the latest events in Ukraine to bring you up to speed.

Russian bridge-building foiled

• UK military intelligence says an entire Russian battalion was wiped out during a thwarted effort to establish a bridge over the Siversky Donets river in the eastern Donbas region
• The governor of the Luhansk region says his forces stopped three Russian efforts to lay down bridges on different days
• Ukraine claims it killed more than 1000 invading troops, but an analyst tells the BBC the true toll is probably much lower
• The Kremlin is yet to comment on the alleged losses

Beyond the Donbas region

• A Russian serviceman accused of killing an unarmed Ukrainian civilian has appeared in court in Kyiv - ahead of the conflict's first trial of a soldier accused of war crimes
• Ukraine says 1.2 million people - including 200,000 children - have been deported from their country against their will since the fighting started - but the BBC's not been able to verify this
• Ukrainians who've ended up in Russia during the conflict have described terrifying interrogations from border guards as they try to leave the country to enter Estonia

In diplomacy

• The defence ministers of Russia and the US have spoken for the first time since Russia began its invasion - with the American side calling for an immediate ceasefire
• The UK has announced new sanctions against the inner circle of Russia's President Putin - including his ex-wife and his alleged girlfriend
• The EU has pledged another €500m (£425m) in military assistance for Ukraine

Image source, .

Ukraine's defence minister has said he hopes to arm a million fighters as the country prepares for a "new, long phase of war".

Oleksiy Reznikov noted in a Facebook post that Ukraine would "need to meticulously plan resources" and "avoid mistakes" in order to win the war. Already, he said, Russia had suffered a "strategic defeat".

The arrival of foreign weapons and "stimulating Ukrainian producers" would help further tip the balance against Russia, he continued.

But before that, Ukraine was "facing extremely difficult weeks ahead".

"Nobody can tell how many. In that period, we will hold the defence primarily with our own resources against the enemy mad with rage," he predicted, in comments translated by our colleagues at BBC Monitoring.

"Increasing pressure of sanctions against Russia and increasing foreign assistance to Ukraine should create, within several months, the conditions under which the Kremlin will finally lose all chances to achieve any success. Then a new window of opportunity will appear for Ukraine. In this extremely hard period, we need unity, cohesion, will and patience," he concluded.

Electricity exports from Russia to Finland are being suspended from 01:00 local time (22:00 GMT) on Saturday.

Finnish grid operator Fingrid said Russian utility Inter RAO was stopping supplies due to "problems in receiving payments for electricity sold on the market".

The announcement comes the day after Finland signalled its intention to join Nato.

Finland only buys 10% of its electricity from Russia, and according to Fingrid it will make up the shortfall by sourcing more power from Sweden, and increasing generation in Finland.

Finland expects to become self-sufficient in electrical energy in 2023, the company added.

Sophie Williams
BBC News, Lviv

Image source, Ukrainian Airborne Forces Command

A Ukrainian military analyst admits that constant attacks from Moscow mean the Ukrainians are on the back foot around the Siversky Donets river – even though they’ve managed to thwart Russian attempts to put down bridges near Severodonetsk.

“The advantage is now on the side of the Russian Federation,” Oleh Zhdanov tells the BBC. “We still can't bring down Russia's offensive pace.”

Zhdanov says it’s “very important” that his side keeps control of this part of the Siversky Donets.

Gaining the area would allow the Russians to make a bridgehead and advance in the direction of the river’s estuary, Zhdanov explains. This would let them encircle the key city of Severodonetsk more fully as they attempt to cut off Ukraine’s whole eastern Donbas region.

The order for soldiers to gain this territory came from the very top, Zhdanov adds.

“They are advancing so hard because it is a political task, because Putin has ordered it,” he says.

As we’ve been reporting today, UK defence intelligence says a Russian battalion lost almost all its armoured vehicles during failed attempts to establish bridges across the river. Russia has not commented.

Image source, .

Image source, EPA

Russian Defence Minister Sergei Shoygu and his US counterpart Lloyd Austin have spoken for the first time since 18 February - before Russia invaded Ukraine.

According to a statement issued by the Pentagon, Austin urged an immediate ceasefire in Ukraine and used the call to emphasise the importance of maintaining lines of communication.

On Wednesday, Austin held talks with UK Defence Minister Ben Wallace.

In a statement, Wallace said the two leaders pledged "to continue to work with unity and resolve to provide Ukraine with what it needs to defend itself against Russia’s unprovoked invasion".