Vice Premier Zhang Dejiang visited the site on Saturday afternoon to inspect the rescue effort, while President Hu Jintao and Premier Wen Jiabao both “made instructions on the rescue work,” Xinhua said. Expressions of concern by top offiicials after mine disasters have become frequent in recent years, as deadly accidents have continued despite repeated efforts to improve safety.

Image Rescuers waited on Saturday to go down a coal mine to search for survivors after a gas explosion at the Xinxing Coal Mine in Hegang, Heilongjiang Province. Credit... Reuters

Mine disasters are regular occurrences in China; the worst previously this year appears to have been a blast at the Tunlan coal mine in Shanxi province in northern China in February, which killed 77 and was the largest such incident since 105 miners were killed in December 2007.

Official data shows that the number of coal mining deaths has been cut in half since 2002, to 3,210 last year, although some mine disasters continue to be covered up.

The explosion on Saturday was unusual in that it involved a large mine operated by one of China’s biggest state-owned companies, the Heilongjiang Longmei Holding Mining Group. Xinhua said that 420 miners had survived and reached the surface, out of 528 who were underground at the time of the blast, a shock so powerful that it partly collapsed mine buildings at the surface.

Most of the deaths in Chinese mines occur in small, unlicensed operations that the national government has tried to shut down. But the authorities often meet resistance from mine owners, who find these operations profitable, and from local officials who want to create jobs and may have corrupt links to the mine owners.