Chinese Premier Wen Jiabao has written to Russian Prime Minister Mikhail Fradkov about pollution in the cross-border Songhua river, pledging to further enhance cooperation with the Russian side to reduce damage from pollution spills.

Foreign Ministry spokesman Qin Gang told a regular news conference in Beijing Tuesday that in the letter, sent in Dec. 4, Premier Wen underscored the importance to the health and safety of the people of both nations in protecting the cross-border water resource.

The pollution spill in the northeastern China's Songhua River was caused by an explosion at a Chinese petrochemical plant early Nov.. It is estimated that about 100 tons of benzene, a harmful chemical, spilled into the river.

China and Russia started jointly monitoring pollution slick in the river last Friday, China's environmental watchdog, the State Environmental Protection Administration (SEPA) said in a statement.

Both sides will also jointly monitor the pollution slick in Tongjiang, where the Songhua and Heilongjiang rivers intersect, the statement said. The Heilongjiang River is called the Amur River in Russia.

Wen introduced countermeasures his country has taken against the accident and noted that China will cope with it in a responsible manner.

China has sent two patches of pollution-relief material to Russia, including water monitoring devices and 150 tons of activate carbon, which will help absorb the chemicals in the river, Qin said.

The Chinese government approved the resignation of Xie Zhenhua, director of SEPA last Friday, who became the highest-ranking official to resign for an environmental incident in China.

Moreover, the senior management of local chemical industry, including Yu Li, head of the Jilin branch of China National Petroleum Corporation (CNPC), was dismissed for his due responsibility for the toxic spill.