BEIJING - China will limit the number of new tailings dams for mining projects and cut down on the use of existing ones to reduce safety risks and ease environmental pressures, the Ministry of Emergency Management said in a notice on its website.

New projects will be encouraged to use existing tailings dams, while relevant departments were asked to tighten their environmental and safety regulations for new mines, it said in its notice late on Friday.

The ministry also asked local governments to cap the number of existing tailings dams within their region, possibly closing older ones if a new tailings dam was needed for mines considered "strategic" or critical to filling a supply shortage.

The Ministry of Emergency Management also said it would work to gradually reduce the number of current tailings dams. Tailings dams that have been out of service for over three years or that have been abandoned must be shut down within a year.

Local governments should also disclose the details of the tailings dams in their regions on their websites or local mainstream media at the beginning of each year, and companies should establish proper emergency response procedures in case of dam failures, the ministry said.

The ministry also prohibited new tailings dams from being higher than 200 metres, within 1 km of residential areas or important facilities, or 3 km from the Yangtze or Yellow rivers.

Tailings dams are the most common waste disposal methods for mining firms, whether they are extracting iron ore, copper or gold. They can tower dozens of metres high and stretch for several kilometres.

China tops the world with nearly 8,000 tailings dams. It has been working on revising its guidelines for tailings dams since a dam failure last year at a Vale SA VALE3.SA iron ore mine that killed more than 240 people in Brazil.

(Reporting by Min Zhang and Shivani Singh; Editing by Tom Hogue) ((min.zhang@thomsonreuters.com; (8610) 5669-2105;))