The contraceptive pill will be sold by an officially-sanctioned UK website from today.

Until now it has been available only on prescription from GPs and clinics.

The doctors running the DrThom website say it is aimed at busy working mothers and those living a long way from a GP.

Easily available: There are fears the Pill will be 'handed out like smarties'

But the development has raised fears that young girls will go online and buy the Pill.

There are also warnings that an internet service cannot carry out the same health checks as GPs  -  and that the side-effect dangers of the drug mean it should not be 'handed out like Smarties'.

Critics fear that attempts to limit sales to women of 18 and over will be abused by young girls too nervous to discuss intimate matters with a doctor.

London GP Trevor Stammers said: 'One knows from other areas of internet use that you can never know who is on the other end of the line.

'There seems to be an open door for abuse of the system by those who are not over 18.'

The DrThom site states that it is the only online medical service registered with the watchdog Healthcare Commission.

It is the first UK-based internet service to sell the Pill, although a number of websites worldwide offer the contraceptive.

Orders will initially be limited to women who have already been prescribed it by their doctor. But DrThom, which already sells sexual infection tests and the morning-after pill, hopes 'very quickly' to start selling to new users.

The service is intended for those aged 18 and over, but DrThom has no way of enforcing this.

Website founder Dr Thomas Van Every, a sexual health expert at London's Chelsea and Westminster Hospital, said orders in which the patient's name does not match that on the credit card will be rejected and it was unlikely a youngster would pay online for medication she could receive free from a GP.

But he admitted there was no way of stopping under-18s circumventing the system.

A girl who had never been prescribed the Pill could use her mother's name and credit card details. Or a woman could buy the Pill for a younger sister or friend.

The company also has no way of confirming whether a customer is already taking the drug and is having regular checks for potential problems.

Dr Van Every, who also runs a private clinic in central London, said: 'We see the DrThom service as part of an ongoing trend - consistent with UK government policy - to help women access contraceptive services as close to home as possible.'

But Dr Stammers, a trustee of Family and Youth Concern and chairman of the Christian Medical Fellowship, questioned whether the online service could carry out the same health checks as doctors.

He pointed out that the Pill can raise blood pressure, and there are risks of potentially fatal conditions caused by blood clots.

'I am sure it will only be a matter of time before someone has a thrombosis or embolism as a result of using that service,' said Dr Stammers. 'The contraceptive pill is not a Smartie. You need to be monitored when you are on it.'

John Smeaton, of the Society for the Protection of Unborn children, said that widespread availability of contraception provided an incentive to become sexually active - putting vulnerable youngsters at risk of sexually-transmitted infections.

GPs are allowed to prescribe the Pill to under-16s. They are supposed to encourage the youngsters to tell their parents, they can prescribe it without parental knowledge or consent if the girl does not wish to involve her family.

Independent clinics and health services that provide medicines, like DrThom, have to be regulated and inspected by the UK's health watchdog - the Healthcare Commission.