A prominent psychiatrist is trying to douse a firestorm of criticism after dozens of people descended on Peking University in protest against his remarks on mentally-ill petitioners.

Sun Dongdong, head of the university's judicial expertise center, ignited public anger by suggesting that 99 percent of people who repeatedly petition the government are mentally ill. The center helps judicial authorities evaluate a person's mental health.

"I extend my sincere, deep apology to those people whose feelings are hurt," Sun said in a statement sent to China Daily yesterday.