Clean-up efforts were under way on Friday to control coal tar contamination in a river in north China's Hebei Province, which is endangering a reservoir supporting Baoding, a city with a total population of more than 10 million, the Xinhua News Agency reported.

The pollution was caused by a traffic accident in north China's Shanxi Province on June 12. A truck carrying 60 tons of coal tar overturned in Fanshi County and spilled its entire load into the Dasha River, which originates in Shanxi, passes through Fuping County in Hebei and empties into the Wangkuai Reservoir 30 kilometers downstream.

Wangkuai is one of two key reservoirs that supply water to Baoding.

Fire engines were sent from Baoding 8.5 kilometers downstream to pump the contaminated water from the river.

The water will be pooled and treated in a closed environment, Xinhua reported.

Clean-up workers had built 51 dams by Thursday to intercept the 60 tons of coal tar amid other measures to minimize the pollution threat downstream.

The dams, 42 in Fanshi County and nine in Fuping County, were built to buy time to treat the polluted water. Clean-up workers also dug holes near the river and diverted the spill into them.

According to official sources, most of the pollutants, primarily phenol, are concentrated within 20 kilometers upstream of the first dam built on the Dasha.

The contaminated stretch entered Fuping on Tuesday. It was moving at about 1 kilometer per hour and by Friday was 20 kilometers away from the urban areas in the county.

Cotton batting, sponge and straw were trucked in to absorb the coal tar in the Dasha River. Activated carbon was also put into the river to absorb the huge amounts of pollutants, sources said.

Rescue workers began putting in place a 15-kilometre-long pipe on Thursday to carry clean water downstream in a bid to ensure that residents downstream would have access to safe drinking water.

So far there have been no reports of people falling ill from the contaminated water, largely because the area's drinking water comes from wells.

The truck was heavily overloaded when the accident happened, but the driver held back the fact that he was carrying coal tar when he reported the accident to traffic authorities, delaying clean-up efforts, Fanshi County officials said.

The truck driver has been detained.

In another development, two people were still missing on Friday after an explosion at a chemical plant in east China's Zhejiang Province on Thursday.

No one was reported killed, and only one person was injured. Financial losses are still being calculated, said Liu Jianshe, a factory official.

The cause of the accident was unclear on Friday night. Officials from the State Administration of Work Safety were investigating at the scene.

(China Daily June 19, 2006)