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 living in the city of Khabarovsk, proposed the dam idea, according to the report.

If the dam went ahead, it would be built on the Fuyuan waterway, which joins the Heilong and Wusuli rivers along the two nations' border, the paper said.

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 of people. The Songhua flows into the Heilong.

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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