Beijing - China plans to invest about 1,4-trillion yuan (about R1 260-billion) in environmental protection in the next five years, state media said on Tuesday, to curb water and air pollution so severe it causes riots and health problems.

The money - equivalent to about 1,5 percent of Gross Domestic Product - is to be spent on measures including control of water pollution, improving air quality in smog-choked cities and halting soil erosion, the official Xinhua news agency quoted He Bingguang, of the State Development and Reform Commission, as saying.

Sewage treatment facilities are to be built in 10 river valleys to dispose of waste water discharged by urban areas and part of the funds will also be used to reduce sulphur dioxide and dust in major cities.

China is home to 20 of the world's 30 most smog-choked cities.

The country has been struggling to curb its environmental degradation, the product of more than two decades of near-double-digit annual growth, as economic development trumps conservation.

Its pollution woes became a subject of international concern last November when a toxic spill poisoned the Songhua river, a source of drinking water for millions.

Under the commission's plan, the huge investment will also go towards building facilities to guarantee nuclear safety.