A Siberian mining region began three days of mourning yesterday after more than 50 people died in a coal mine accident and a rescue effort that ended in tragedy.

After initially reporting that six rescuers had died during attempts to reach miners, officials said yesterday that one had been found alive and taken to hospital for treatment.

But news of his survival was a small consolation for a community devastated by the loss of 51 lives, including those of 46 miners, in the worst mining accident in Russia in more than a decade.

Officials said it appeared Thursday's accident at the Listvyazhnaya mine in the Kemerovo region had been caused by a methane explosion.

Investigators launched a series of probes into possible safety violations, with senior managers at the facility arrested.

Flags flew at half-mast outside official buildings in Kemerovo and grief-stricken relatives of the victims wept outside the snow-covered mine site.

"I can't carry on," one woman said, as families gathered in sub-zero temperatures.

A former worker at the mine, Denis Timokhin, told independent TV channel Dozhd safety violations wee frequent at the facility, accusing management of forcing miners to work despite high methane concentrations.

"If you don't want to work, quit," he said. "No safety protocols, all sensors are plugged with bags."

Accidents are a part of life in the mining region, and some residents in the village of Gramoteino next to the mine laid flowers at a memorial dedicated to rescuers killed in a previous mine accident in 2000.

Officials said the Listvyazhnaya mine filled with smoke on Thursday morning after the apparent explosion, with 285 people underground.

Miners described a frantic scramble to evacuate.

"I stretched out my hands, they couldn't find me on their own, because the visibility was bad," another said.