HARBIN - Rescuers are digging a new tunnel to reach 11 trapped miners in northeast China after their efforts were hampered by dense gas, a local official said Monday evening.

Rescuers are also racing to clear the shaft where ceiling collapses occurred after a fire broke out at a coal mine in Shuangyashan, Heilongjiang Province, on Saturday, said Wang Ju, the city's coal mine management chief.

The new passage will bypass the fire-affected and collapsed areas to reach the part where the trapped miners might be.

However, it may take three to four days to dig such a tunnel, said Wang.

After two days of rescue efforts, rescuers have been unable to reach the miners due to a dense concentration of carbon monoxide in the shaft.

Experts believe air and water access is available where the miners are trapped, and it is possible that they are still alive.

Fire broke out at around 9 a.m. Saturday when 13 miners were working at a shaft of the Longshan Coal Mine in Youyi County of Shuangyashan. Two of the miners managed to escape.

The cause of the accident is under investigation.