China's top environment watchdog confirmed on Saturday that pollution levels did not rise during the spring ice thaw of the Songhua and Heilong rivers, which were heavily polluted last November after a severe chemical spill.

Benzene-related chemicals, which were the main pollutants of the spill, remain at a safe level in the Songhua River in northeast China and the Heilong River, the border river between China and Russia, during the spring thawing period, according to a statement released by the State Environmental Protection Administration (SEPA).

Non-stop surveillance work conducted on a daily basis by environment workers from Heilongjiang and Jilin provinces shows that water quality in the two rivers is steady and no pollution has occurred, according to the statement.

Both rivers have now thawed, but the benzene, nitrobenzene and aniline levels of the two rivers do not exceed the national standards of both China and Russia, the SEPA statement said.

The Songhua River, a tributary of the Heilong River, which is also called the Amur River in Russia, was heavily polluted after an explosion upstream at a chemical plant on November 13 in Jilin City, capital of Jilin Province.

The incident caused some 100 tons of benzene-related chemicals to spill into the river, endangering the water supply for millions of residents along the river and forcing many cities to suspend water supply.

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

From March 4 to 22, both Chinese and Russian monitoring teams took samples of water, ice and silt from different sections of the rivers and found that pollutants did not exceed the national standards of the two countries, according to the statement.

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

The Songhua River has been listed as one of the country's most heavily polluted rivers in need of urgent intervention.

In March, the State Council approved a program to curb its pollution from 2006 to 2010.

(Xinhua News Agency May 8, 2006)