China's drug safety watchdog has blacklisted 23 websites, which were found to have been selling fake drugs or to have published illegal adverts that exaggerated the benefits of their products.

The websites, some of which claimed to be sponsored by research institutions of renowned universities, were identified by the State Food and Drug Administration (SFDA) on its website (www.sda.gov.cn) on Monday.

The problematic drugs sold by the websites ranged from those claimed to be able to cure body odour, skin diseases, diabetes, and tumors, according to the SFDA.

One of the website (www.nrgnqkfw.cn/12315tf), which claimed to be sponsored by the rehabilitation center of bone diseases with China Medical University, sold a drug to treat necrosis of the thigh bone. The website can still be visited, but its 24-hour hotline is continually engaged.

China Medical University has been changed into the Peking University Health Science Center (PUHSC) after it was incorporated into the university in 2000. The operator of the PUHSC told Xinhua that the center did not have a rehabilitation center for bone diseases.

An SFDA spokeswoman, Yan Jiangying, said the SFDA has reported the 23 websites to the Ministry of Industry and Information Technology for further investigation.

The websites would be closed if their illegal activities were confirmed. The SFDA will work with the public security authorities and postal services to investigate the case.

According to China's Criminal Law, those producing or selling fake drugs could face death penalty if the drugs resulted in death or serious damage.

Yan admitted that it was difficult to completely stop illegal websites. "Frequently we found that shortly after a batch of websites were shut down, illegal websites appeared at some other places."

She said only those with the SFDA license of Internet medicine business can sell over-the-counter (OTC) drugs to individuals.

"So far, only ten websites across China have been issued with the license," she said.

The SFDA has published the names of the 10 websites on its website and urged the public to check against the list before they buy drugs online.