Dozens of angry people stormed the gates of Peking University on Friday to protest a professor’s remarks on rural petitioners, the Associated Press reports. Petitioners are frustrated Chinese, mostly from poor rural areas, who journey to Beijing to air grievances against their local governments.

The protesters were upset by comments by Sun Dongdong, a professor at the university’s prestigious law school, in an interview with China Newsweek, a magazine published by a Chinese news agency. The magazine’s March issue quotes Mr. Sun as saying that 99 percent of China’s petitioners are mentally ill. He also supported forced hospitalizations of mentally ill petitioners, according to The Wall Street Journal.

The Chinese government says it receives three million to four million letters and visits from petitioners each year. Human-rights groups estimate the number is well over 10 million, according to the AP. Local officials sometimes send thugs or police officers to chase petitioners to the capital and look for ways to discredit the complaints.

“There is an overflow of cases involving petitioners being forced into mental hospitals,” a lawyer, Li Heping, told the AP. “After being labeled as a mental-health patient, one loses all rights.”

Mr. Sun is reportedly involved in drafting China’s first mental-health law. Protesters are concerned that his comments could affect national policy.

The protesters began gathering outside Peking University over a week ago. On Friday about 40 people tried to rush through the gates. Security forces stopped them and loaded them onto buses.

In a public apology, the law professor said he was only talking about the petitioners he had met as a mental-health professional. —Mara Hvistendahl