Russia said Sunday that trains carrying more bodies of Ukrainian soldiers were due to depart towards the Ukrainian border, escalating a spat with Kyiv over a prisoner of war swap.

A Russian defense official Sunday said trains carrying the remains of Ukrainian soldiers would be dispatched to an area near the Ukrainian border, stepping up tensions between Moscow and Kyiv over a long simmer dispute over a war prisoner swap.

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