A river in northern China polluted with dangerous chemicals after heavy flooding on Wednesday will be cleaned up as soon as possible, local officials said on Thursday.

Flooding washed over 1,000 barrels of explosive chemicals into the Songhua River in the Jilin Province early on Wednesday, officials said. The river, a tributary of the Amur River in Russia, is the main source of drinking water for Jilin, the province's second-largest city.

Ecologists and experts are working around the clock to prevent a possible environmental catastrophe, a spokesperson for the Chinese Environmental Protection Ministry said.

The containers carried away from a local chemical plant in Jilin Province held more than 160 metric tons of methyl chloride, an extremely explosive chemical gas.

Emergency workers are currently trying to remove the barrels and local environmental protection authorities are monitoring the water quality in the river.

In November 2005, an explosion at a plant owned by the Jilin Petroleum and Chemical Company caused 100 tons of potentially lethal benzene to spill into the Songhua River. The incident forced the shut-down of water supplies to nearly 4 million people. The spillage caused substantial environmental damage in Russia's Far East, as a huge slick of chemicals was carried down the Amur.