BEIJING - At least 31 miners were killed and 78 remain trapped 500 meters (yards) underground following a gas blast at a mine in China, state media said on Saturday.

The blast ripped through the mine around 2.30 on Saturday morning, when there were 528 people at work, but 419 got out safely, the official Xinhua news agency said.

The Xinxing mine is in Heilongjiang province, which borders Russia. It is owned by the Heilongjiang Longmei Mining Holding Group, and produces 12 million tons of coal a year, Xinhua said.

Vice Premier Zhang Dejiang is heading to the site of the accident, and Chinese President Hu Jintao and Premier Wen Jiabao have given instructions about the rescue work, a sign of official concern about the latest in a long string of disasters in the world's deadliest mining industry.

Rescue teams are already on site, with 60 people hunting for the missing miners, Xinhua said.

Lax safety standards and strong demand for resources have made China's mines the deadliest in the world, despite a government drive to clamp down on the tiny, unsafe operations where most accidents occur.

More than 3,000 people died in mine floods, explosions, collapses and other accidents in 2008 alone.

(Reporting by Emma Graham-Harrison; Editing by David Fox)