President Volodymyr Zelenskyy said that roughly 1,300 Ukrainian troops have been killed since Russian forces invaded the country.
The president gave the figure in a meeting with reporters on Saturday, according to the Associated Press.
Zelenskyy also called for a ceasefire to kick off peace talks between the parties.
Earlier on Saturday, the president called on Russian troops to release Melitopol Mayor Ivan Fedorov, who was abducted on Friday, Kyiv said.
“The demand is simple — to release him from captivity immediately,” Zelenskyy said.
The issue was raised in calls with French President Emmanuel Macron and German Chancellor Olaf Scholz, the Ukrainian leader added.