A worker walks past the gate of Pingyu Coal & Electric Co. Ltd. in Yuzhou, central China's Henan Province, Oct. 17, 2010. [Xinhua]

The death toll from a coal mine gas leak in central China's Henan Province has risen to 31 after five more bodies were found, rescuers said Monday.

But six others are still trapped underground, and their identities have been confirmed, a spokesman with the rescue headquarters said.

Rescuers said Sunday that chances of survival for the trapped miners were very slim, and they could be buried in coal dust.

More than 2,500 tonnes of coal dust smothered the pit after the gas leak, which hampered the rescue, said Du Bo, deputy chief of the rescue headquarters.

The gas outburst happened at 6:03 a.m. Saturday when 276 miners were working underground in the mine in Yuzhou City. A total of 239 workers escaped but 21 were found dead and 16 were trapped.

An initial investigation showed that 173,500 cubic meters of gas leaked out in the accident.

Liu Wenbin, a deputy chief engineer of the company that owns the mine, was in the pit when the accident happened. He organized the escape.

"At around 6 a.m., I felt there was something wrong with the airflow in the shaft, and one of the team captains told me he also felt it and had already reported the problem," said Liu.

The mine is owned by Pingyu Coal & Electric Co. Ltd., a company jointly established by four investors, including Zhong Ping Energy Chemical Group and China Power Investment Corp..

Rescuers descend underground at the coal mine in Yuzhou City, central China's Henan Province, Oct. 16, 2010.[Xinhua]