Dr Veerakathy Harindra, the director of Portsmouth Hospitals NHS Trust's genito-urinary medicine clinic, believes the kits are fuelling an epidemic of sexually-transmitted disease among young people by creating the impression they can be easily treated.

They also mean that people are failing to get checked for other, more serious diseases, because they are only thinking about whether they have chlamydia or not, and not incurable diseases such as HIV or herpes.

He has spoken out as The News reveals hundreds of teenagers are catching and spreading infections – including a 12-year-old girl with herpes – because they are not practising safe sex.

Dr Harindra fears that people who buy the £25 over-the-counter kits may think a negative result means they are free of any infection, when they could have serious diseases.

And even if the chlamydia test is positive people can buy a course of antibiotics, meaning other diseases go unnoticed.

Children as young as 13 can get the morning-after pill free at pharmacies. The local NHS is about to invest in home-testing chlamydia kits but Dr Harindra backs this move because youngsters will get treatment and advice through the NHS.

Dr Harindra said: 'Over-the-counter tests are not the answer. You have got to make young people understand their sexual behaviour, how and why they acquired their infection. We have got to constantly educate young people to protect them.

'Over-the-counter tests can lull people into a false sense of security. If the result is negative they might think they are alright – but what about the other infections?'

Boots spokeswoman Helen Savage said: 'Any patient who comes in for the treatment has to have a consultation with the Boots pharmacist to ensure they are suitable for private treatment.

'Our pharmacists have been trained to offer advice to customers and all patients will be advised that they can also visit their GP or genito-urinary medicine clinic to access treatment and advice.'