China and Russia will jointly monitor cross-border waterways for pollution following a major Chinese chemical spill last year that led to contamination in both countries, state press said Wednesday. "The agreement marks a substantive step in environmental protection co-operation between China and Russia," the China Daily quoted the head of the State Environmental Protection Administration, Zhou Shengxian, as saying.

Zhou signed the agreement with Russia's Natural Resources Minister, Yuri Trutnev, in Beijing Tuesday, the paper said.

Some of the waterways to be placed under joint surveillance are the Heilong, Wusuli, Erguna and Suifen rivers, as well as Xingkai Lake.

The Heilong river was one of the waterways contaminated after an explosion at a chemical factory in northeast China in November led to 100 tonnes of highly toxic benzene and nitrobenzene spilling into the eco-system.

The chemical slick flowed hundreds of kilometres along the Songhua river in China until it reached the Heilong on the China-Russia border.

"To prevent recurrence of such accidents, experts from the two countries will regularly exchange information and work together," the paper said.

Russian scientists said fish with bleeding ulcers had been caught as recently as last week near the China border and attributed the poisoning to the Songhua river debacle.

Zhou said he hoped the water monitoring agreement would mark the start of a broader environmental protection program between the two countries.

"China and Russia need to jointly develop comprehensive environmental protection," Zhou said.