About half of urban psychiatric patients on the Chinese mainland who need hospitalization cannot afford it, said a veteran mental health expert.

Citing national research, Zhang Mingyuan, vice-chairman of the China Disabled Persons' Federation, also said a quarter of the patients find medication too expensive.

Zhang, also a member of the Chinese People's Political Consultative Conference (CPPCC) National Committee, urged the government to boost investment and efforts to give those in need full access to mental health treatment.

He made the comment on the sidelines of the continuing annual session of the nation's top political advisory body.

Currently, less than 2 percent of health funds are spent on mental health in many developing countries, including China, the World Health Organization (WHO) has estimated.

"The situation is even worse in China's vast countryside, where patients with severe conditions are left untreated, posing a danger to others as well," Zhang, a United States-trained psychiatrist, warned.

"It'll be best for the government to greatly improve psychiatric care, since it will help with social stability and public security," he said.

According to a Beijing-based mental health institution, about 82 percent of the 1,515 people who were accused of criminal offenses and underwent psychiatric evaluation there from 1984 to 1996 suffered from mental disorders.

Currently, at least 100 million Chinese on the mainland suffer from various mental illnesses, including 18 million serious patients, according to statistics from the Ministry of Health.