Russian officials say that Moscow is still awaiting confirmation from Kyiv on a planned exchange of 6,000 bodies of soldiers killed in action.

(Reuters) -Ukrainian President Volodymyr Zelenskiy vowed on Sunday to press on with prisoner exchanges with Russia and said any failure by Moscow to uphold humanitarian accords cast doubt over U.S. and other efforts to end the more than three-year-old conflict.

A large-scale prisoner exchange between Russia and Ukraine -- the only concrete outcome of peace talks -- was thrown into doubt Saturday after Moscow and Kyiv accused each other of delaying and thwarting the swap.