China has still to recover 15 hazardous radioactive sources and must focus on the fight to keep drinking water clean and contain chemical spills after May 12's massive earthquake, a senior official said on Friday.

But Wu Xiaoqing, vice environment minister, insisted the situation was under control after experts and equipment were drafted in from nearby areas, and there had been no accidental releases of radiation or uncontrolled hazardous leaks.

The government has located a total 50 radioactive sources in the disaster area, which is home to China's chief nuclear weapons research lab in Mianyang, as well as several secretive atomic sites, but no nuclear power stations.

"Thirty-five of the radiation sources have been recovered, and the location of another 15 has been confirmed, but they have not yet been recovered," Wu told a news conference in Beijing.

"Three are buried in rubble and another 12 are in dangerous buildings, which staff cannot go into," he added. "At present, tests from the scene show that there has yet to be an accidental release of radiation."

The official Xinhua agency had earlier this week reported over 30 radiation sources were buried under the rubble in Sichuan. Wu declined to comment on whether there were might be more, as yet unlocated, radiation sources.

The ministry, which lost over 700 million yuan (50.8 million pounds) worth of equipment and offices in the quake, is also struggling to contain more commonplace dangers from the region's array of heavy industry.

"Environmental supervision capacity in the area is badly below what is needed ... A number of hidden troubles will loom large in the recovery process," Wu said.

"The quake-hit area has a big concentration of high-risk industries. There are over 100 chemical plants in Chengdu, Deyang, Mianyang, Guangyuan, Ya'an, Meishan and Aba," he added, listing areas near the epicentre.

There were also 59 producers of hazardous waste in four of these areas alone, he added, although all facilities were currently considered secure.

DRINKING WATER KEY

The ministry's priorities were ensuring safe drinking water, improving management of hazardous chemicals, and preparing for adequate environmental supervision during reconstruction.

"Ministry of Environmental Protection will ... do its best to overcome difficulties to ensure drinking water safety and nuclear safety," Wu said, adding that the ministry was working to prevent local authorities using toxic chemicals and ensure the carcasses of dead livestock were properly disposed of.

Most drinking water in the area is of the same quality it was before the quake, although samples in one area had higher than usual concentrations of petroleum, Wu said, which could be the result of fuel leaking from crushed cars and generators.

Air quality was also normal across the quake zone, despite fears that the collapsed buildings could throw up asbestos or fine dust particles that can damage lungs.

But Wu cast a shadow over the impoverished area's economic future, saying that chemical and petrochemical projects would be reviewed before reconstruction work was allowed to go ahead.

($1=6.945 Yuan)