Beijing (AsiaNews/Agencies) - The death toll in a massive coal mine explosion in central China has risen to 166, making it the worst mining disaster in China in recent history, local officials said on Wednesday. Officials said rescue efforts were being blocked by fires and toxic fumes in the Chenjiashan Coal Mine (Shaanxi province), which was hit by the huge gas explosion on Sunday.

Yan Mangxue, the party secretary for a nearby village where 14 of the dead miners are from, said: "This morning they made the announcement to a handful of reporters at the command centre. They made the conclusion because there's no chance anyone would survive. They haven't told the relatives yet. The relatives still don't know."

He said local officials like himself had been asked to begin finding the families in their jurisdiction and informing them that their relatives were dead.

Yan said around 100 bodies still remained in the mine.  "It could take about 10 days before all the bodies are brought up," he said.

A total of 293 workers were underground at the mine, when the accident happened on Sunday. Some 127 miners escaped.  Investigators determined that a back-to-back gas blast and coal-dust explosion knocked out all ventilation systems in the pit, making survival for those missing all but impossible.

In a separate accident, a government news agency reported that 13 people were killed and three missing in an explosion early Wednesday in a coal mine in the southern province of Guizhou.

More than 7,000 workers are killed each year in China's coal mines, considered the world's most dangerous. Fires and explosions often are blamed on disregard of safety rules or lack of required equipment needed to remove natural gas that seeps from the coal bed. The government has promised repeatedly to reduce the carnage in coal mines. But officials say severe nationwide power shortages might be increasing  pressure for mines to raise coal production, boosting the risk of accidents.