Gao warned about complacency, saying the ecological disaster highlights the need for "perfect" contingency plans to meet such disasters.
Tons of the toxic chemical benzene flowed into the river after an explosion at a chemical works on 13 November, forming an 80-kilometer-long slick.
The latest Chinese city to be affected is Yalin, which has closed its water supply network. Upstream, the city of Harbin has reopened its water system after a five-day closure.
The slick is heading downstream and is expected to affect Russian settlements along the Amur River in the coming days, particularly the city of Khabarovsk, which has a population of about 700,000.
A slick of toxic benzene and other chemicals is moving from China's Songhua River toward the Amur River in Russia's Far East. Russian authorities fear the consequences when the 80-kilometer-long toxic slick reaches the city of Khabarovsk, which relies on the Amur for its water supply.
Officials say supplies of clean water and filtering charcoal are being stockpiled in Khabarovsk. Russian authorities have warned that more than 1 million people living along the Amur could be affected by the contaminants. The spill is the result of an explosion on November 13, 2005, at a Chinese chemical plant in the city of Jilin....(more)