The number of Ukrainian soldiers killed on the battlefield in the four years of war with Russia is 55,000, President Volodymyr Zelensky has said.

Zelensky announced the figure in an interview with France 2 TV on Wednesday. Additionally, a large number of people are considered officially missing, he said.

While both Kyiv and Moscow have regularly published estimates of the other side's losses, they have been reluctant to detail their own. However, the BBC has confirmed the names of almost 160,000 people killed fighting on Russia's side in Ukraine.

US President Donald Trump has been leading efforts to end the war that began with Russia's full-scale invasion of its neighbour on 22 February 2022.

Special US envoys Steve Witkoff and Jared Kushner, Trump's son-in-law, held talks with Russian and Ukrainian negotiators in the capital of the United Arab Emirates, Abu Dhabi, for a second day on Thursday in an effort to try and thrash out the details of the US-proposed peace deal.

It was the second such trilateral meeting and the talks had been detailed and productive, Steve Witkoff wrote on X, but significant work remains.

The most difficult issue is territory, with Russia demanding that Ukraine cedes the rest of the eastern industrial region of Donbas that Moscow does not currently control.

Trump often says thousands of Ukrainians and Russians die unnecessarily every week. Western intelligence agencies also publish estimates, which are impossible to verify.

The last time Zelensky gave an update on Ukraine's casualties was in December 2024, when he put deaths at 43,000.

In his interview with French television, he said: In Ukraine, officially the number of soldiers killed on the battlefield - either professionals or those conscripted - is 55,000.

The official number of dead cited by Zelensky is considerably lower than Ukraine's total losses. As he said himself, a large number of people are registered as missing.

As of six months ago, Ukraine's interior ministry had recorded more than 70,000 people as officially missing - both soldiers and civilians - but the breakdown is never given.

The true figure may be higher - information about the number of dead is highly sensitive and affects morale.

Across Ukraine, military graves are prominent in all cemeteries - marked with blue and yellow national flags. They often have an image of the soldier in uniform engraved on the headstones.

We have also met mothers still searching for their sons, who never returned from battle.

Often, they cling to hope that the men are prisoners of war, captured and held in Russia somewhere but not on any official lists.

Access to Russian prisons for organisations like the Red Cross is highly restricted.

The alternative is that the missing men have been killed and their bodies not recovered from territory now controlled by Russia, or that their remains have not yet been identified using DNA testing.

Every so often, the two countries arrange an exchange of bodies - in addition to swapping prisoners of war - but there has been nothing at all since last August.

Another agreement on swapping prisoners was reached in the Abu Dhabi talks, Witkoff announced. It involved the exchange of 314 prisoners - the first such exchange in five months, he said.

While significant work remains, steps like this demonstrate that sustained diplomatic engagement is delivering tangible results and advancing efforts to end the war in Ukraine, Witkoff added.

The talks began as Russia renewed attacks on Ukraine after a week-long pause that Trump had asked Vladimir Putin to observe as a fierce cold swept Ukraine.

It has been targeting the country's energy sector, leaving thousands without power and hearing as temperatures dropped to -20C (-4F).