A gas explosion at a coal mine in northern China (search) killed 33 people, the latest disaster to strike the country's accident-prone mining industry, the official Xinhua News Agency reported Friday.

The blast occurred at 4:20 p.m. Thursday in Yangquan, a city in the northern province of Shanxi (search), the report said. Twenty-eight miners were killed in the explosion at the Daxian Sankeng Colliery, as were five people who descended into the pit trying to rescue them.

About 40 other miners working underground at the time were able to escape, Xinhua said.

The explosion comes less than two weeks after a blast in central China killed 166 miners — the nation's deadliest mining accident in years.

In the latest accident, thick toxic gas clouded the mine shaft until early Friday, the agency said. The Daxian Sankeng Colliery — a small, licensed mine — produces 150,000 tons of coal a year, it said. Yangquan is about 200 miles southwest of Beijing (search).

An investigation was under way.

China's coal mines are the world's deadliest, with more than 4,500 miners reported killed this year in fires, floods and other disasters. The government says China accounted for 80 percent of all coal mining-related deaths worldwide last year.

With each new disaster, the government vows to implement more reforms. Many accidents are blamed on a disregard of safety rules or lack of required equipment needed to remove natural gas that seeps from the coal bed.

Mine owners and local officials are frequently blamed for putting profits ahead of safety, especially as China's soaring energy needs increase the demand for coal.

China also bans independent trade unions, which have successfully pushed for better safety in other countries.

"Mine owners, driven by profit, often violate regulations on safe practice, reduce investment in protective facilities to lower the cost, gang up with local officials and disregard miners' lives," Li Qiang, executive director of New York-based China Labor Watch, said in a statement earlier this week.

The group urged China to allow non-governmental organizations to monitor work safety.