BEIJING – Toxic wastewater was flushed untreated into a river in southern China, prompting the government to cut water supplies to 28,000 people for at least four days, a local official and a Chinese newspaper said Monday.

The official China Daily said that a power plant on the upper reaches of the Yuexi River in Sichuan province was to blame for the pollution, which prompted environmental officials to suspend water supplies to the town of Guanyin last week.

A town leader reached by telephone said 28,000 people had been without water since Tuesday evening. He said a power plant in nearby Xinqiao county had discharged untreated wastewater directly into the Yuexi. The man asked that his name not be printed because he said town regulations prevent officials from talking to the media.

Fire trucks were bringing clean water to residents but supplies were short, he said. There were no reports so far of people sickened by the pollution, he said.

A man who answered the phone at the Xinqiao Power Plant said poor quality coal may have been partially to blame for the pollution and that an investigation was underway. The plant had temporarily halted power generation, said the man, who would only give his surname, Yang.

An employee with a local water supply company noticed the river water had turned yellow last Tuesday, the China Daily said. Tests showed it was polluted with high levels of fluoride, nitrogen and phenol, also known as carbolic acid, it said.

The incident follows a spate of spills in recent months, the most serious being an explosion at chemical plant in November that dumped chemicals into the Songhua River, the source of drinking water for tens of millions of people living in northeastern China and Russia.

Local authorities were criticized for reacting too slowly to the chemical plant explosion and delaying disclosure to the public.

Under new regulations enacted earlier this month, serious accidents must be reported directly to the Environmental Protection Agency, known as SEPA, or to the State Council, China’s cabinet, within an hour.

After more than 25 years of breakneck growth, China is in the midst of an environmental crisis that has continued to worsen as local authorities fail to enforce regulations meant to counter severe air and water pollution.

Officials at SEPA and at the Sichuan Environmental Protection Agency refused to comment on the latest report.