BEIJING -- China's top environment watchdog expects to be closing down serious polluters along the northeast Songhua River during a campaign this month that will inspect every factory along the polluted waterway.

The campaign, which runs through September, will target all chemical plants, paper mills, food processing companies, pharmaceutical factories and sewage treatment plants, according to the State Environmental Protection Administration (SEPA) on Tuesday.

Both the provinces of Jilin and Heilongjiang will be responsible for the campaign as the river runs through their jurisdictions. They have been ordered to inspect all factories that discharge waste into the Songhua and its tributaries.

The central government have also asked their provincial counterparts to suspend construction projects and production activity that has not undergone an environmental assessment. Companies can resume operations only after they have followed due process of assessment.

The plan calls for companies that consume too much water and cause heavy pollution to be replaced. Businesses with promising market potential but are poorly equipped to handle their waste should have their pollution control facilities upgraded.

Enterprises discharging more than 65 percent of a county's total industrial wastes will be closely monitored.

Officials who attempt to cover-up or pass the buck during the clean-up campaign will be charged with obstruction. Companies that violate environmental laws will be exposed in the media. Their managers may be prosecuted and charged with a criminal offence .

SEPA initiated the campaign following repeated chemical spills in the Songhua and its tributaries.

Ten tons of a toxic chemicals were dumped into Songhua's tributary Mangniu River in Jilin by two truck drivers from Changbaishan Jingxi Chemical Company in August.

Last November, about 100 tons of polluted waste containing benzene spilled into the Songhua River after a chemical plant explosion in Jilin. The incident forced cities along the river, including Harbin, to temporarily cut water supplies to 3.8 million people.