Guangdong Health Department spokesman Wu Xiaoming said further investigations were needed to determine the cause of death of nine other people who had been injected with armillarisin A containing diglycol, a substance that can cause kidney failure.

Mr Wu said experts needed to determine whether the victims had exhibited four symptoms associated with the defective medication: pain in the kidneys and digestive system, and damage to the kidneys, nervous system and liver.

He said the hospital was treating five other patients who had been injected with the drug. Two were in serious condition.

Sun Yat-sen University's No3 Affiliated Hospital was the only hospital in the province that administered the drug, Mr Wu said. 'The company won the supply contract and since the drug had been approved by the government, the doctors did not have any concerns about prescribing it,' he said. 'They began using the drug on April 19 and stopped on April 30 when problems arose.'

State media has reported the hospital had a hepatitis department which replaced its former medication with the cheaper armillarisin A.

Hospital vice-director Cai Daozhang said doctors were not aware the drug company had used diglycol, an industrial chemical, instead of propylene glycol. 'The ingredients are not indicated on the box,' he said.

Another source said no doctor would knowingly prescribe fake medicine even though they were known to receive kickbacks from drug companies to push certain drugs.

A western doctor said the armillarisin A, which was only used in China, had probably passed quality tests because of corruption, but also because drug firms used cheaper raw materials to cut costs; or 'somebody just signed [the certification] without looking'.

'It is common knowledge that China has the worst quality control. They are worse than India,' the doctor said.

Xinhua reported that the drug company produced the batch of medication in March and supplied the drug mainly to Guangdong and Shanxi .