"We are ceasing fire everywhere but inner regions of DPR. Any attempt of [Kiev soldiers] to leave the 'cauldron' [Debaltseve encirclement] will be stopped. I have already given this order," Alexander Zakharchenko told reporters.
"There is not a single word about Debaltseve in [Minsk] agreements. That means that Ukraine simply betrayed 5,000 people in the 'cauldron'," Zakharchenko said.
Debaltseve, one of Ukraine's biggest railroad junctions, has become the site of intense fighting between Kiev and southeastern Ukrainian pro-independence fighters.
Kiev denies claims that its soldiers are encircled in Debaltsevo.
During Thursday's Minsk talks, the leaders of Kiev and the breakaway republics of Donetsk and Luhansk managed to sign a deal, stipulating a ceasefire from Saturday night, prisoner swaps, weaponry withdrawal and constitutional changes in Ukraine.
Donetsk forces announced readiness to cease fire and allow surrounded Kiev soldiers to leave the Debaltseve area "on respectful conditions."
An earlier ceasefire agreement reached by the warring sides last September broke down, with clashes intensifying in recent weeks. Debaltseve, one of Ukraine's biggest railroad junctions, has become the site of intense fighting. According to reports, up to 10,000 Ukrainian troops remain surrounded after attempting to recapture the contested town.