China plans to spend 4 billion yuan ($500 million) this year to provide 20 million of the country's rural population with safe drinking water, a vice minister of water resources was quoted on Saturday as saying.

China has 21 percent of the world's population and only 7 percent of its water resources. The leaders of the world's most populous nation have made clean water for the people a top priority.

The central government will treat contaminated water resources from 2006 to 2010 to provide potable water to 100 million rural residents, the official Xinhua news agency quoted Vice Minister Jiao Yong as saying.

He did not elaborate other than saying the water resources of many rural residents were contaminated with fluorine and arsenic.

From 2000 to 2005, the government spent 22 billion yuan and provided rural residents in central and western China with drinking water, Xinhua said.

By the end of 2004, the government had resolved the plight of 56 million people who had difficulty accessing drinking water and provided safe drinking water to another 11 million, it said without providing further details.

Ecological damage has accompanied China's industrial boom with many state-owned factories ignoring pollution hazards and dumping toxic industrial waste into China's rivers and lakes.

China's top pollution watchdog has pledged to get tougher with polluters after an explosion at a chemical plant in northeast China last November poured 100 tons of cancer-causing benzene into the Songhua river.