Illegal HIV test kits imported from China for sale online could give an incorrect diagnosis, a Government health watchdog warned today.

The Medicines and Healthcare Products Regulatory Agency (MHRA) plans to shut down six websites based in the UK which have sold kits without the necessary CE quality mark.

The websites also sold non-compliant testing devices for other sexually transmitted infections, including hepatitis, gonorrhoea, chlamydia and syphilis.

Almost 500 people have already bought the kits, which allow users to test themselves for infection in their own homes.

People have been browsing the internet to buy the products as an anonymous alternative to being tested in a clinic.

Some of the kits came with no instructions at all, while others were confusing or insufficient.

The Health Protection Agency (HPA) has written to people who have bought the kits, warning them that they do not comply with UK guidelines.

The purchase details were contained in sales records uncovered during the MHRA investigation.

The agency regularly scans the internet to catch websites selling illegal devices.

In order to comply with EU rules, kits must carry the CE kite mark and the name and address of the manufacturer or an EU-based representative.

It is illegal in the UK to sell any kits to test for HIV, but not for other sexually transmitted infections.

The HPA stressed that free and confidential tests are available on the NHS.

Susanne Ludgate, the MHRA's clinical director of services, said: "As far as self-test kits for sexually transmitted infections are concerned, purchasers should check that any kits purchased from internet sites are CE marked, which should denote conformity with the relevant European legislation.

"We're concerned that there may be a number of self-test kits being sold online that may not be compliant with the relevant piece of legislation and we're urging people not to consider the internet as a method of anonymous testing.

"These kits may be unreliable and there is a significant risk they could be providing the user with a false result."

Dr Fortune Ncube, a consultant epidemiologist at the HPA, said: "The HPA has sent letters to members of the public across the UK who are known to have purchased these kits online to inform them that the result may be unreliable."

:: Anyone worried about a self-test kit they bought online can contact their GP, pharmacist or sexual health clinic for advice, or email