Beijing - A Peking University professor apologized after hundreds protested in front of the campus against his claims that people who petition the government are mentally ill, local media reported Wednesday.

Professor Sun Dongdong was quoted in the March 23 edition of China Newsweek magazine as saying that 99 per cent of people who repeatedly petition, or make complaints to the government, are mentally ill.

"Putting them in hospital is the best insurance we have, as they are a danger to society and themselves. The best way to protect their human rights is to keep them indoors, give them treatment and promote their spiritual recovery," he was quoted as saying.

Nearly 300 people rallied outside the university on Monday and Tuesday, according to activists quoted in the Hong-Kong based South China Morning Post.

Sun apologized in a statement on the China News Service on Monday afternoon.

"Some of the content, due to an inappropriate use of language, caused some dispute and misunderstandings. I deeply regret this. If some of the content hurt some people's feelings, then I sincerely apologize. I also truly hope they (the petitioners) will be able to solve their problems through legal channels," he said.

Under China's petition system, citizens are allowed to challenge government or judicial decisions by filing grievances with designated bureaus, which are then required by law to provide a response.

But there have been many reported cases of petitioners being sent to mental institutions by locals authorities to silence them.

The state-run Beijing News reported last December that residents of Xintai in Shandong province were institutionalized after complaining about local corruption and the unfair seizure of property.

They were released only after agreeing to give up their causes, the article said.(dpa)