Volodymyr Zelensky said that about 43,000 Ukrainian soldiers have been killed since the start of the large-scale Russian invasion, in a rare acknowledgment of the scale of human losses in the country.
The Ukrainian president said in a post on social media that 370,000 injuries had been reported, although this number includes soldiers who were injured more than once and it was said that some injuries were minor.
He also claimed that 198,000 Russian soldiers were killed and 550,000 others were injured.
The BBC was unable to verify figures for either side.
While both Kiev and Moscow regularly publish estimates of the other side's losses, they are reluctant to provide details of their own losses.
The new figure represents a significant increase in Ukrainian deaths since the beginning of the year.
Zelensky last provided an update on casualties in Ukraine in February, when he put the death toll at 31,000.
It is believed the Ukrainian president was forced to admit after US president-elect Donald Trump wrote on social media that Ukraine had “ridiculously lost” 400,000 soldiers, while nearly 600,000 Russians were killed or wounded. Trump did not say where these numbers came from.
The new president, who has long made clear that he wants to end the war, said too many lives had been “needlessly wasted.”
Zelensky's estimates of Russian losses are similar to those presented by senior Western officials, who estimate that Russia has suffered about 800,000 casualties, including dead and wounded.
The British Ministry of Defense says Russia suffered 45,680 casualties in November alone, more than in any month since the start of its large-scale invasion in February 2022.
According to the latest British Defense Intelligence estimates, an average of 1,523 Russian soldiers are killed and injured every day.
On November 28, she says, Russia lost more than 2,000 men in one day, the first time this had happened.
Moscow disputes these numbers. The Kremlin claimed in a statement that Ukrainian losses were “several times higher” than Russian losses.
Outside Russia, there is a consensus that Russian casualty numbers Much higher than Ukraine due to “meat grinder” tactics..
Recent developments in the war have only increased the death toll.
Russian forces continue to make gradual advances along the eastern front line, seizing about 2,350 square kilometers (907 square miles) of territory in eastern Ukraine and in the Kursk region in western Russia since the beginning of the year.
Ukrainian forces maintain control of a small swathe of Russian territory they captured during a surprise attack on Russia in August.
The Russian Ministry of Defense says that more than 38,000 Ukrainian soldiers were killed or wounded in Kursk alone, a number that cannot be verified.
Russia annexed Crimea in 2014. Eight years later, it launched a full-scale invasion of Ukraine and occupied territory in the south and east of the country.
Zelensky mentioned Ukraine's war dead in a broader post about the prospects for a definitive end to the war.
This comes after talks in Paris on Saturday with French President Emmanuel Macron and Trump, who sought to capitalize on views held by about a quarter of Americans that the United States provides too much support to Ukraine.
During the campaign, Trump repeatedly said he could end the war between Russia and Ukraine “in one day” — but he has not yet specified how he intends to do so.
In his post, Zelensky stressed that any peace agreement must be supported by effective international guarantees for his country’s security.
He said he told Macron and Trump that Kiev needed a “lasting peace” that would not be “destroyed by Moscow in a few years.”
In response to Trump's call for an immediate ceasefire, the Kremlin said it was open to negotiations, but the conditions for a cessation of hostilities were set by Russian President Vladimir Putin in June.
His demands included that Ukraine give up more of its territory and abandon its ambitions to join NATO, which Kiev rejected.
