An expert panel from the Water Resources Ministry has travelled to the region to investigate the feasibility of the dam, the China Daily reported.

Russian authorities, who are particularly concerned about the potential contamination of the water supply for more than 600,000 people in the city of Khabarovsk, proposed the dam idea, according to the report.

Chinese foreign ministry spokesman Qin Gang confirmed that China was considering building such a dam but did not say who would foot the bill.

"What China is going to do is do what it takes to reduce the possible impact of the pollution to Russia to the minimum level," Qin told a regular briefing.

"So the Chinese side agreed to give positive consideration, including setting up a dam in the Fuyuan waterway and such similar engineering projects."

The Fuyuan waterway joins the Heilong and Wusuli rivers along the two nations' border.

Qin did not give any other details about the project but said China and Russia were in consultation.

Widespread contamination prevention efforts have been underway in China and Russia since an explosion on November 13 at a PetroChina chemical factory in the northeast Chinese province of Jilin.

The accident led to the spillage of 100 tonnes of the carcinogens benzene and nitrobenzene into the Songhua River, one of China's longest waterways and a source of water for millions. The Songhua flows into the Heilong.

The slick on Thursday arrived in the northeastern Chinese city of Jiamusi, the second largest city in Heilongjiang province with over two million people, the state news agency Xinhua said.

As of early Thursday, the toxic levels of the chemical slick remained up to 7.35 times above national safety levels, Xinhua said.

Officials had turned off the public water system in Jiamusi earlier this week, repeating the action taken for the much larger provincial capital of Harbin last month.

Prime Minister Wen Jiabao, who has already apologised to Russia for the accident, was again forced to address the environmental concerns on Wednesday while on a European tour.

"We have informed the Russian side and supplied technical aid and necessary equipment," Wen told reporters during a visit to the Slovakian capital of Bratislava.

"We have already taken effective measures, such as the reinforcement of monitoring and the river's warning system. We are also going to take effective steps to eliminate the pollution and assure drinking water for the population."

Authorities in Khabarovsk have nearly finished building a dike to protect the city from the toxic slick, Nikolai Yefimov, head of the local branch of the WWF environmental group, said Wednesday.

The dam will block a river channel upstream from Khabarovsk in the hope of diverting the 130-kilometre (81-mile) slick away from the city.

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