The death toll from a coal mine blast in northern China has risen to 166, Xinhua news agency said on Wednesday, confirming one of the worst disasters to hit the country this year.

The spokesman for the mine declared all the 166 miners were killed, Xinhua said, confirming what authorities had been expecting in the days since Sunday's accident.

More than 120 workers escaped the state-owned Chenjiashan coal mine in Shaanxi province after the explosion, or what may have been back-to-back explosions. Many were seriously injured.

High temperatures and a buildup of toxic gas had slowed the search for bodies at the mine where until Wednesday 65 workers had been known to have been killed, with 101 trapped and presumed dead.

"The coal mine has a high density of gas, due to intergrowth of coal, oil and gas. Its coal bed remains responsive to fires. The mine used to suffer a fire every three to six months and the shortest break between two fires was 24 days," Xinhua said.

Sunday's blast was the worst since a September 2000 explosion in southwestern Guizhou province killed 162 people.

"In an environment with a high density of coal, gas and carbon monoxide, it's impossible that the miners still trapped underground can survive," Huo Shichang, head of the provincial coal mine industry administration, told a news conference earlier on Wednesday.

Another coal mine blast killed at least 13 miners on Wednesday morning in the southwestern province of Guizhou, the State Administration of Work Safety said on its Web site www.chinasafety.gov.cn.

The death rate for every 100 tonnes of coal produced in China was 100 times that of the United States, Xinhua said on Tuesday.

Source: Xinhua/agencies