At least 31 people have died and around 90 remain trapped following a major gas explosion in a coal mine in northeast China's Heilongjiang province, state media said.

The China Daily quoted the mine's owner, Heilongjiang Longmei Mining Holding Group, as saying 415 miners escaped the accident, which occurred at 02:30 local time on Saturday after a gas buildup.

The part of the mine where the workers are trapped is about 500 meters underground.

The paper said Chinese President Hu Jintao and Premier Wen Jiabao have issued urgent instructions on rescue work, and that Vice Premier Zhang Dejiang is on his way to the site.