The active phase of the anti-terrorist operation to eliminate militants who refused to lay down arms is taking place near the town of Krasny Lyman, eastern Ukraine, operation spokesman Vladyslav Selezniov told Interfax-Ukraine on Thursday morning.

"The active phase of the anti-terrorist operation is taking place there at the moment," he said.

Last night, Ukrainian soldiers scattered leaflets in Krasny Lyman ordering local militants to lay down arms, Selezniov said.

"The militants refused to do so, prompting the forces of the anti-terrorist operation to take up their positions in order to block the adversary," the spokesman said.

"The latest information available suggests that none of the Ukrainian servicemen was killed or injured last night, while the militants suffered heavy losses," Selezniov said, declining to provide further details.