The Ukrainian Security Service has confirmed the tentative agreement to exchange 225 militants for 150 Ukrainian troops.

"I can say we have resolved the last differences on the POW exchange. We will exchange 150 for 225," Markiyan Lubkivsky, an adviser to the Ukrainian Security Service, told Interfax-Ukraine.

"As for the 150 people held by the militants, this figure is not final," Lubkivsky said.

Lubkivsky also reiterated that it is important for Ukraine to return all Ukrainian citizens who are now held captive.

He recalled that the Minsk negotiations have not ended yet and it is too early to speak about any final agreements.

Alexander Zakharchenko, the head of the self-proclaimed Donetsk People's Republic, said on Thursday that an agreement had been reached on large-scale POW exchange with the Ukrainian authorities.