Four Ukrainian military servicemen were released from captivity by militants on Saturday, February 20, the Ukrainian presidential administration's spokesman for the anti-terrorist operation (ATO), Oleksandr Motuzianik, said.

"Ukraine has got four of its soldiers freed from captivity," he said at a briefing in Kyiv on Sunday.

Motuzianyk stressed that the exchange took place with the assistance of the Ukrainian Security Service.

Earlier reports said that, Kyiv and the self-proclaimed Donetsk People's Republic (DPR) swapped their captives under a 'three-for-six' formula. Later, Ukrainian President Petro Poroshenko confirmed the release of three Ukrainians from captivity.

MP Iryna Gerashchenko, a Ukrainian representative in the humanitarian subgroup in the Trilateral Contact Group for settling the conflict in Donbas, said earlier that as many as 137 Ukrainian citizens were being held captive in Donbas territories not controlled by Kyiv.