Health authorities have started to probe the alleged 1.69 million yuan ($276,000) in bribes from Sanofi-Aventis to 503 doctors in Beijing, Shanghai, Hangzhou and Guangzhou.

The Shanghai Health and Family Planning Commission has ordered local medical institutes to look into media reports that their doctors took bribes from the French pharmaceutical giant in 2007, the commission told China Daily on Monday.

A female staff member at Shanghai's Minhang District Center Hospital, one of the hospitals listed in the reports, said a probe has started, but she would not disclose details.

Officials at Ruijin Hospital and Zhongshan Hospital, both in Shanghai, said they were carrying out a thorough investigation with local health authorities, according to Xinhua News Agency.

In Beijing, the city's commission for discipline inspection is investigating the hospitals involved in the incident, joined by local authorities in health, public security and procuratorate, Zhong Dongbo, deputy director of the Beijing Health Bureau, said on Monday.

"The hospitals involved have been asked to do an investigation themselves first," he said.

An information official surnamed Yang from Peking University Third Hospital, one of the hospitals reportedly involved in the case, confirmed that the hospital is investigating the incident.

According to the 21st Century Business Herald, in 2007, Sanofi paid 80 yuan to doctors every time they prescribed patients with Aprovel or CoAprovel medicines to control high blood pressure during in a clinical trial.

Zhai Xiaomei, a member of the medical ethics committee under the National Health and Family Planning Commission, said "pharmaceutical companies tend to run these trials on more and more medical products".

"But it is inappropriate and against the rules for them to pay doctors directly instead of to hospitals, who do the clinical trials for them," she said.