Seven bosses held responsible for two blasts which killed 249 coal miners were sentenced yesterday to prison terms ranging from three to six years.

But the nightmare in China's coal mines continued, with 11 miners killed yesterday in a gas blast at a mine in northwest China.

The blast, in Gansu Province, brought the death toll in the nation's coal mines to more than 100 in five days.

Explosions in the provinces of Yunnan, Heilongjiang, Shanxi and Jiangxi at the weekend killed 88 miners.

Investigations show all the mines continued production even after the government ordered them to halt.

Another seven workers were killed on Monday when a coal heap collapsed and buried them in the southwestern province of Guizhou.

Yesterday's blast was in the No.1 coal mine in Tanshanling Town, Wuwei City, 180 kilometers from Lanzhou, the Gansu Province capital.

The seven bosses sentenced were held responsible for fatal gas explosions in northwest China's Shaanxi Province and Xinjiang Uygur Autonomous Region.

Liu Shuangming, former director of the Chenjiashan Coal Mine in Tongchuan City, Shaanxi, was sentenced to five years and six months and Wang Youjun, former deputy director and chief engineer of the mine, to five years over a gas blast that killed 166 people on November 28, 2004.

Yaozhou District People's Court of Tongchuan City heard that Liu and Wang had asked the miners to work despite being aware of the risks to their lives.

Of 293 miners working underground when the blast occurred, only 127 working near the entrance were rescued, including 45 who were injured in the blast.

Liu and Wang were blamed for the accident and arrested on December 9, 2005, in Tongchuan.

The Chenjiashan mine is a state-owned company with 3,400 employees and a capacity of 2.6 million tons of coal a year.

Also yesterday, a court in Xinjiang sentenced Jiang Jinpeng, former board chairman of the Shenlong Coal Mine Limited Company to six years in prison and four others to terms from three to five years.

The five were found responsible for a gas blast on July 11, 2005, in Shenlong Coal Mine of Fukang County, 62 kilometers from Urumqi, the regional capital, when 87 people were working in the shaft. Only four survived.

The blast could have been avoided if the management had taken effective measures to withdraw miners and cut electricity underground immediately after detecting the high gas density, according to local officials.

Chinese coal mines suffer frequent explosions, flooding and cave-ins, claiming about 6,000 lives a year.

Unsafe small coal mines account for two-thirds of the total deaths in mine accidents, government figures show.

In September, Zhao Tiechui, director of the State Administration of Coal Mine Safety, said China would seal off 2,652 small mines, each with an annual output of less than 30,000 tons, this year and another 2,209 next year.

But last month, An Yuanjie, from the State Administration of Work Safety, said plans to close all unsafe small mines had been delayed because of opposition from local governments.