Beijing  - A woman infected with H1N1 influenza has died "accidentally" at a hospital in the eastern Chinese city of Hangzhou, state media on Thursday quoted officials as saying.

Medical staff found the unidentified 34-year-old woman dead in a restroom at the No 1 People's Hospital in Hangzhou's Xiaoshan district on Wednesday, local health officials told the government's Xinhua news agency.

The woman had shown signs of recovery since she was admitted to the hospital on June 23 and her temperature was normal for the past week.

Her only remaining flu-like symptom was occasional coughing, the agency said.

It said local police and health experts were investigating the death, which would be China's first confirmed fatality from H1N1 if the virus is deemed to have caused her death.

The agency did not explain why officials had called the death accidental.

China has confirmed 866 H1N1 infections, with 340 under current hospital treatment and three people quarantined at home, the health ministry said. The other 523 people had recovered fully from the virus, it said.

Beijing confirmed 21 new cases on Wednesday, including seven children at a primary school, the ministry said.

Earlier this week, Liang Wannian, vice director of the ministry's emergency office, said China's rising number of cases made it "very likely" that it would report its first death from the virus in the near future.

The World Health Organization said it had recorded 77,201 confirmed cases of H1N1 flu in more than 100 nations by Wednesday, including 332 deaths. (dpa)