Cervical cancer experts warned young women today against buying DIY smear tests over the internet.

Dr Anne Szarewski, a clinical consultant at the Wolfson Institute of Preventive Medicine in London, spoke out as online pharmacy DrThom launched the kits.

She said they could lead to women under 30 being told they have the sexually-transmitted infection that causes cervical cancer when it would actually clear up on its own.

The new test detects changes in genetic material in cells affected by human papillomavirus (HPV), which causes most cases of cervical cancer.

The £115 service is being aimed at busy career women, those who find going for smear tests embarrassing or younger people who fall outside the current age group for screening on the NHS.

Women in Scotland, Wales and Northern Ireland receive NHS screening from the age of 20 but those in England are only eligible from the age of 25.

Screening ages have been the subject of debate after TV star Jade Goody died last year from cervical cancer aged 27.

Dr Szarewski said: “In young people, everyone is going to test positive. The rate of HPV is high but transient... it comes and goes.”

She said women whose results suggested something was wrong could be left feeling anxious.

“For women under 30 I don't think there's a call for HPV testing. It's going to create a lot of worry among women.”

Professor Peter Sasieni, a Cancer Research UK epidemiologist, said while the charity supported making smear tests more accessible, it could not support the DrThom test “because there is a lack of published data on how effective this would be”.

“HPV infection in young women is extremely common and mostly harmless. It is not clear what proportion of women under 25 would test positive but it could exceed 15%,” he said.