BEIJING, CHINA - A LARGE spill of toxic slurry from a mine has turned part of a northern Chinese river black and fouled it with dangerous chemicals, state media said on Monday.

The accident occurred on Friday in Shaanxi province when the sides of a catchment basin for toxic tailings, or mining debris, at a vanadium mine collapsed after heavy rain, the Shaanxi-based Chinese Business View reported.

The collapse sent a deluge of black toxic mine tailings and slurry flooding into the Xiangdang river near the town of Yinghua in Shanyang county, it said.

Yinghua has a population of about 14,000 people, according to the local government website.

The accident covered more than 2km of the river bank in a toxic black sludge that caused local residents to experience difficulty breathing, the report added.

Although the spill was quickly contained, several more kilometres of the river experienced dangerous levels of nitrogen and chemical oxygen demand, key measures of water pollution.

The mine was owned by the Hengyuan Mining company, the report said.

Vanadium is an alloy used in steel production that is toxic in concentrated levels.

China's rapidly growing economy has combined with lax environmental regulation to create severe water pollution.

More than 70 per cent of the country's waterways and 90 per cent of its underground water are polluted, according to previously released government figures.

Toxic spills in China are common.

In one of the worst recent examples, an explosion at a chemical plant spilled around 100 tonnes of the carcinogens benzene and nitrobenzene into the Songhua River in northeastern China in November 2005, killing eight people and injuring 60 others.

Water supplies for millions of people living along the river were suspended for days, with some of the polluted water flowing into Russia. - AFP