The benzene-related pollutants in northeast China's Songhua and Heilong rivers remain at a safe level during the spring thaw period, China's State Environmental Protection Administration (SEPA) said Saturday.

Polluted water in Songhua River reaches Harbin, the capital of northeastern Heilongjiang province November 24, 2005. [Reuters]

"The water quality in the Songhua and Heilong rivers is steady and no pollution has occurred," read a statement from the SEPA.

The thaw period had finished, but the benzene, nitrobenzene and aniline contents in the two rivers did not exceed the national standards of both China and Russia, said the SEPA.

The Songhua River, a tributary of the Heilong River which is also called Amur River in Russia, was heavily polluted last year after a chemical plant explosion upstream on November 13, causing some 100 tons of benzene-related pollutants to spill into the river and endangering the water supply for millions of residents along the river.

Since then, Chinese environmental protection departments have been closely monitoring the changes of water quality in the two rivers. China and Russia have also conducted several joint monitoring exercises.

From March 4 to 22, the two sides took samples of water, ice and silt from the different sections of Songhua River and found benzene-related pollutants did not exceed the national standards of China and Russia, according to the statement.

"At present, China and Russia are discussing how to enhance environmental protection along the rivers bordering the two countries," said the statement.