BEIJING - The country's environmental watchdog will suspend reviews of all new industrial projects in Qujing, Southwest China's Yunnan province, until the city cleans up its toxic chromium slag and remedies polluted soils, a senior official said on Thursday.

The Ministry of Environmental Protection is also preparing to launch a nationwide campaign to target illegal dumping and stockpiling of hazardous waste before the end of this year, according to Zhang Lijun, deputy minister of environmental protection. 

Enterprises involved in the production of chromium and polycrystalline silicon, and in the disposal of sewage sludge and electronic waste will be placed under special scrutiny, he added.

Under Chinese law, all industrial projects must undergo environmental reviews before being approved for construction. The regional ban for Qujing, which will put a brake on its economic expansion, came as a punishment after a local chemical plant illegally dumped more than 5,000 tons of highly toxic waste in June.

The dumping contaminated nearby water sources, caused the deaths of livestock and threatened the safety of drinking water for cities downstream.

"This is not an isolated case. It reflects a widespread oversight on the treatment and disposal of hazardous waste in the country," said Zhang.

The large amounts of toxic industrial waste are polluting soils and water sources, and posing threats to public health, he said.

The latest national pollution census, in 2007, showed the country produced 45.74 million tons of hazardous waste that year. During the 12th Five-Year Plan (2011-2015), the amount is expected to increase at an annual rate of 5 to 7 percent, as the country's demand for industrial materials will continue to grow, Zhang said.

"However, every year, only about 8 million tons receive proper treatment, less than 20 percent of the total amount," he said.

Zhang cited limited treatment capacity, the high cost of proper disposal and slack supervision by environmental authorities as causes of the failure to control the use of dangerous chemicals.

The ministry set the end of 2012 as a deadline for all chromium plants to properly treat all of their stockpiled slag. Toxic waste produced after 2006 has to be cleared up by the end of this year. Those who fail to meet the deadlines will be ordered to halt production.

An independent investigation by environmental organization Greenpeace shows that there are still more than 140,000 tons of chromium slag stockpiled at Yunnan Luliang Chemical Industry, the polluting company in Qujing.

Tests showed that the groundwater near the plant has an extremely high concentration of carcinogenic sexivalent chromium. Nearby villagers have complained about a higher than normal rate of cancer in their communities.

Some environmentalists welcomed the ministry's move. 

Ma Tianjie, a toxics campaigner from Greenpeace, said: "The timetable to properly dispose of stockpiled toxic waste is very important. But it is also essential for the ministry to disclose relevant information so the public can participate in the supervision."