Environmental safety officials say the area around the site of a chemical plant explosion in northeast China is free of pollutants.

Officials had conducted repeated tests on groundwater around the Xiguang Chemical Plant since the blast on April 6, said a statement from the government of Harbin, capital of Heilongjiang Province.

Tests showed the blast has caused no pollution in the Songhua River or the surrounding area, said the statement on Saturday.

Tanks containing the raw materials for producing diluting agents exploded around 3.30 PM, injuring two workers and destroying four tons of dimethylbenzene and cinnamene at the plant in Songbei District of Harbin.

The plant, a collectively-owned factory, which used to do paint mixing, had an annual production capacity of 20 tons of diluting agents.

Probes showed it was operating illegally after being ordered to shut down in October last year. The blast occurred just three days after it resumed unlicensed production on April 3.

The site is just four km from the Songhua River, a tributary of the Heilongjiang -- or Amur River -- which flows along Sino-Russian border. There are no homes within a kilometer of the plant.

A team of inspectors from Harbin environmental protection bureau and the public security bureau have been probing the cause of the accident.

Police have been trying to trace the plant's legal representatives, who disappeared after the explosion. Environmental protection officials have monitored air and water quality.

About 100 tons of benzene-based chemicals spilled into the Songhua River after another chemical plant blast in neighboring Jilin Province on Nov. 13 last year. It was one of the worst cases of river pollution since the founding of new China in 1949.

(Xinhua News Agency April 17, 2006)