Anti-Terrorist Operation military spokesman Oleksandr Motuzianyk has said Russia-backed militants claim to have found bodies dressed in military uniform in the Mariupol sector of operations, but added it's too early to say whether they are the bodies of three Ukrainian marines who went messing on January 8. He said the information must first be confirmed by expert analysis.

"If the claims from that side are that bodies have been found wearing uniforms … It's too early to say, until the corpses have been examined and identified," Motuzianyk said during a briefing on Thursday in Kyiv. He said would neither confirm nor deny the deaths of Ukrainian marines.

"It's too early to say, until the corpses are returned to the Ukrainian side and a forensic examination is conducted and the bodies are identified," he said.

Media earlier reported the deaths of Ukrainian troops and talks are underway to return the bodies to a place under control of Ukrainian troops.