Pro-Russian separatists have so far handed over about 1,200 prisoners-of-war to the Ukrainian side under the terms of a cease-fire agreement, President Petro Poroshenko said on Monday.
The two sides are meant to exchange all their POWs under the terms of the cease-fire accord, clinched last Friday.
Poroshenko was speaking during a visit to Mariupol, a port city in the east of Ukraine which the rebels advanced towards last week before the cease-fire took effect.