At least five people have been accidentally infected with HIV at a hospital in China after a doctor reused dirty needles during treatment.

The doctor at the Chinese medicine hospital in the eastern city of Hangzhou is under criminal investigation, according to the local health authority.

The government statement said a "serious medical incident" had occurred at the Zhejiang Provincial Hospital of Traditional Chinese Medicine, reported the South China Morning Post.

The AIDS-causing virus is believed to have spread when the doctor violated procedure by failing to dispose of syringes after use, transferring the infection from one HIV positive patient to at least five others.

Internet users in China reacted with shock to the news, stoking long-standing fears HIV could be spread by poor medical practice.

However, most media reports and social media posts published in Chinese about the incident were swiftly censored, according to AFP.

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The health authority said it had learned of the five infections on 26 January, but did not disclose how many people might have been exposed to the virus in total, or what the original treatments were for.

The Independent has contacted the large hospital, whose website claims it is "well known nationwide for its longest history and largest scale with the best technical capacity in Zhejiang Province", for comment.

Hangzhou, in Zhejiang province, is around 100 miles from Shanghai.

China had around 500,000 cases of HIV and AIDS at the end of 2014, according to a 2015 UN report, and the Chinese government has announced new efforts to contain the spread of the virus with a five-year plan.