Rescue teams in northeastern China are trying to recover 15 miners still trapped following an explosion that killed 134 of their co-workers. 

The blast at Qitaihe in China's Heilongjiang Province happened at a time when China is stocking up on coal supplies ahead of the approaching winter.

With the Chinese government reporting about seven thousand miners killed on the job each year, China has the world's worst mine safety record. Wenran Jiang is a political science professor at the University of Alberta. He says the statistics have challenged a government that is trying to boost worker safety while keeping the economy booming.

"China uses a lot of energy, so therefore [there are] a lot of energy-related accidents. Almost every other week, we have such accidents," he said. "These are actually partly [caused by] the industrialization process, and partly due to the market-driven, all-for-money drive by local governments."

The government has enacted numerous regulations to improve mine safety, but international labor advocates say these have been largely ignored for reasons including corruption, and the pressure on mine operators to fill wintertime energy demands.

The mine at Qitaihe where Monday's blast occurred is operated by a conglomerate of state-owned coal companies. The cause of the explosion is under investigation.

The blast occurred as officials in Heilongjiang Province continued to deal with the after-effects of another major industrial accident.

Authorities on Monday warned residents of the provincial capital, Harbin, it was still not safe to drink tap water, which was turned off last week after 100 tons of toxic chemicals including benzene were spilled into the Songhua River by a chemical factory explosion earlier this month. The new warning came despite state television images showing the provincial governor drinking a glass of tap water, after the pumps were turned back on on Sunday.

The Songhua River supplies most of Harbin's drinking water. The water was turned off for several days to allow an 80-kilometer-long toxic slick to flow past the city of almost four million people.

Concerns on Monday turned to China's border with Russia, where the toxic spill is expected to arrive soon.