The State Environmental Protection Administration demanded that the companies clean up their operations.

The enterprises, along with six sewage treatment plants singled out for criticism, operate along the Yangtze River, Yellow River, Huaihe River and Haihe River, according to SEPA vice director Pan Yue.

Mengniu Dairy's branch in Dengkou County, Inner Mongolia Autonomous Region, has operated without wastewater processing facilities ever since it began business in December, 2005, and it discharges effluent into the Yellow River without treatment, SEPA said.

The dairy plant also expanded its annual capacity to 150,000 tons from 30,000 tons without approval, Pan said.

The Zhongyuan chemical company under Sinopec Corp's Zhongyuan oil field company failed to use disposal facilities, and its wastewater contained excessive ammonia and nitrogen, Pan said.

SEPA will recommend punishment for those responsible for the pollution, the official said.

The agency also suspend construction projects that have not gone through environmental assessments in six cities, two counties and five industrial parks along the four rivers as the water was found to be heavily polluted.