A drug suspected of causing adverse reactions in 61 patients at the Shanghai No 1 People's Hospital was a fake version of the real medicine, according to the State Food and Drug Administration (SFDA).

The SFDA made the announcement late on Wednesday via a statement on its website.

The organization had launched an investigation after 116 patients were given the medicine on Sept 6 and Sept 8 and 61 of them experienced negative symptoms, including pain, red eyes and unclear vision. The patients thought they were receiving injections of Avastin for macular degeneration.

After the incident, Swiss pharmaceutical company Roche and the Shanghai drug assessment body carried out an investigation into the drug used in the incident.

The examination found that the drug labeled as Avastin batch B6001B01 was "fake", according to the SFDA statement.

The SFDA did not say whether the fake drug was of an inferior quality.

The case has been transferred to relevant authorities for further investigation and the departments and individuals responsible for the purchase of the fake drug will be severely punished, the statement said.

The SFDA has requested its branches across the country to supervise drugs used in medical institutions. Those medicines not approved by the administration should be taken out of circulation and their purchase investigated, the SFDA said.

Avastin received approval from China's SFDA in February for use on the Chinese mainland in the treatment of colorectal cancer but it has not yet been officially sold in the Chinese market.

The drug cannot be obtained through formal channels on the Chinese mainland, Cao Yong, a spokesman with the Shanghai Roche Pharmaceutical Company, was quoted as saying in the National Business Daily.

Avastin has not yet been approved for use in the treatment of eye diseases but reports said it has been effective in the treatment of macular degeneration and has been used in many countries.

"Any kinds of drug can only be sold in the market after a process of strict medical experiments, while the forged versions may skip some of those procedures, something that may cause severe problems," said Tang Jianli, a lawyer from Shanghai Haida Law Office, who is experienced in medical disputes.

The Shanghai No 1 People's Hospital said on Sept 13 that most of the patients who suffered adverse reactions had improved. Ten had fully recovered and been discharged from hospital.

The hospital could not be reached for comment on Thursday.