An explosion at a state-run coal mine in northern China killed 42 people and trapped 66 others on Saturday, in yet another mishap for the country's beleaguered mining industry.

More than 500 people were working in the Xinxing mine, which is located in Heilongjiang province near the border with Russia, when the explosion occurred around 2:30 a.m. local time.

Wang Xingang, who was rescued from the mine, told the official Xinhua News Agency that he was knocked unconscious by the blow.

"When I regained consciousness, I groped my way out in the dark and called for help," said the 27-year-old electrician

He was one of 389 people who escaped the mine immediately after the explosion, according to a statement issued by the State Administration of Work Safety.

Thirty-one miners were rescued, while six are in hospital in serious condition. The rest were trapped 500 metres underground. Footage showed that the rescue effort was hindered because one of the entrances to the mine was blocked. Rescuers were forced to go in from another entrance. Gas buildup, and communication links were all cut off, further hampering the search.

Footage broadcast on television showed smoke swirling above the mine after the explosion, which was likely caused by gas build-up. Another image showed a nearby building collapsing after the explosion.

The mine is about 450 kilometres northeast of Harbin, the provincial capital. It has more than 88,000 employees according to its website.

It is owned by the Hegang branch of the Heilongjiang Longmei Holding Mining Group, one of more than 500 state-owned enterprises.

Saturday's blast showed that the government is still struggling with improving safety, while maintaining output. China's mining industry is considered the most deadly in the world. Coal has become vital to China's booming economy and the country uses coal to produce three-quarters of its electricity.

China has become a hot bed of major mining accidents in recent years.

From January to October this year alone, there were 11 major accidents in Chinese coal mines, many of them gas explosions, which killed 303 people, according to government statistics.

In February, an explosion at the Tunlan coal mine in Shanxi province killed 77 people in what was considered China's worst industrial accident in a year.

Many of these accidents are blamed on a failure to comply with safety regulations, such as poor ventilation.

While large government-run mines are considered safer than smaller, private mines, officials have had difficulty imposing safety regulations on the 16,000 private operations, which are unregulated.

Chinese officials closed about 1,000 smaller mines last year alone, a move that they say has cut the average number of miners killed a day in half, to six.

With files from The Associated Press