A gas leak at a steel plant in northern China killed 17 workers on Wednesday and a further 27 were being treated in hospitals, state media reported.

It was believed they had been poisoned by carbon monoxide after a blast furnace vent burst open at the plant in Zunhua City, about 150 km (93 miles) east of Beijing, the official Xinhua news agency said.

Those still in hospital were in stable condition, it added.

Local authorities ordered the company, Ganglu Iron and Steel Co. Ltd., to halt production.

Ganglu, with 7,000 employees, has an annual output of 3 million tonnes of steel products, Xinhua said.

China's breakneck growth in the past three decades has transformed the once-starving country into the world's fourth-largest economy, but has also brought a flood of deadly industrial accidents.

A total of 101,480 Chinese died in all kinds of workplace accidents last year, according to government figures.