Illegal HIV test kits imported from China and sold online could give an incorrect diagnosis, a health watchdog has warned.

The Government's Medicines and Healthcare Products Regulatory Agency is to shut down six UK-based websites that have been selling kits without a 'CE' quality mark. They also sold non-compliant testing devices for infections such as hepatitis, gonorrhoea, chlamydia and syphilis.

Almost 500 of the kits, which enable users to test themselves, have been bought. The instructions that came with some kits were confusing or insufficient, while others had none at all.