Beijing (AsiaNews/Agencies) – Thirty-three workers were killed after a gas explosion at a coal mine in China's northern Shanxi province, work safety administration officials said on Friday.

Seventy-one miners were in the shaft when the blast occurred on Thursday afternoon at Nanlou township near the city of Yangquan, the bureau said in a statement.

Twenty-eight miners were killed in the initial explosion and five others died during a rescue attempt, it said. Everyone else escaped.

The accident comes less than two weeks after 166 people were killed in a coal mine in neighbouring Shaanxi province in the country's worst mining disaster in 44 years. A gas explosion in October killed 148 miners in central Henan province.

The Nanlou mine produces 150,000 tons of coal a year and was licensed to operate, Xinhua news agency quoted the provincial supervision centre of coal mine safety as saying.

China, the world's biggest producer and consumer of coal, has significantly increased coal production in the past year to meet the demands of rapid industrialisation. Critics and miners say lives are being sacrificed in the quest for energy.

More than 7,000 workers are killed each year in China's coal mines, considered the world's most dangerous. Labour rights groups say the real figure could be around 20,000 as many accidents are unreported in an effort to keep mines open and to avoid costly fines for fatalities.

China's appalling mine safety record also highlights the dismal plight of workers in the nominally communist country who do not enjoy the right to form independent labour unions or undertake collective bargaining.