An official from the health authority said that disease-related online forums had an obligation to post accurate knowledge, in response to the escalating scandal over China's search giant "selling" its online forums to some private hospitals.

Baidu's Tieba online forums have been hit by controversy after it was revealed that the search giant sold administration rights to health forums, and possibly others, to private firms. The National Health and Family Planning Commission is concerned about the problems, Mao Qun'an, a spokesman with the health ministry, said at a press briefing on Friday.

"We have asked Baidu about the incident. We hope Baidu can make Tieba a platform which could offer accurate information on diagnosis, treatment and recovery of diseases," said Mao.

Members of the hemophilia forum on Baidu Tieba lodged complaints that the board had been sold to a private hospital that promoted itself in the forum, removed references to competitors, and allegedly banned the forum's original administrators from posting.

Members of the high blood pressure and thyrotoxicosis Baidu forums also reported that their boards had been sold to private companies, raising the possibility of sensitive data being mined for profit and misleading information.

Baidu was also accused of allowing private hospitals to attract patients through paid listing services that directed Internet traffic to the hospitals' websites.

Baidu made an announcement on Tuesday, saying that "the supervision of disease-related forums' operation is particularly important" and Baidu Tieba "will only be open to authoritative public service organizations rather than to those seeking business opportunities."

Baidu's announcement did not relieve public anger.

A total of 36 nongovernmental organizations have signed a joint letter on Thursday, asking Beijing Administration for Industry and Commerce to punish Baidu for violating advertisement laws.

Baidu has misled patients by promoting unqualified hospitals and doctors and it should stop displaying health-related adverts as regular search results, according to the joint letter.

Baidu stated that it has replaced the administrators of the hemophilia forum with staff from Hemophilia Home of China, an NGO dedicated to helping hemophilia patients, making HHC the first NGO to run a disease-related forum.

 "We have encouraged some of our affiliated organizations to cooperate with Baidu to regulate some boards," Mao said.

Mao said that cooperation between specialized medical organizations and network media could make it convenient for patients to share information.