Rescuers toiled deep underground in the debris of a collapsed Ukrainian mine searching for 12 people still missing after a huge explosion, officials said, according to Independent Online.

The 12 were believed to have been near the epicentre of Sunday morning`s methane blast, about a kilometre below the surface of the Karl Marx mine in eastern Ukraine.

"The search for the 12 miners is continuing," the emergency situations ministry said in a statement.

A spokesperson for the mine safety agency, Marina Nikitina, said work was hampered by rising ground water due to damage to water pumps.

"The water is rising but it is still possible to work," she said.

Independent Online