They say some online pharmacies are selling potentially-harmful drugs without asking to see a prescription or giving medical advice.

Someone is going to have very serious harm to their health and eventually someone is going to be killed

Dr Griffith Edwards, National Addiction Centre

By registering websites in the US and posting drugs from abroad, companies are able to bypass UK laws.

Advertising prescription-only medicines direct to the public and selling them without a prescription is illegal in Britain.

'Serious harm'

In the UK, Prozac, for example, can only be bought with a prescription from a doctor.

High Street pharmacists make sure the anti-depressant is dispensed and sold safely.

But it can be obtained without prescription via the internet in a few days.

Doctors are concerned that internet traders could be putting lives at risk.

They say there is no way of checking that drugs bought in this way are safe, or even what they claim to be.

"My fear is making these drugs accessible without due regard for their suitability, without the monitoring, without the warning, without the working along with the person, is not just a little bit worrying," Dr Griffith Edwards of the National Addiction Centre told the BBC.

"Someone is going to have very serious harm to their health and eventually someone is going to be killed."

Legal loopholes

UK lawyers hired to protect reputable online pharmacists are also concerned. They want legal loopholes to be closed.

They say it is almost impossible to prosecute unscrupulous traders, especially when they post drugs from abroad.

Drugs lawyer Louise Forward told the BBC: "It's easy for these companies to set up, it's easy for them to close down and re-open other sites once they do start being investigated, and there is a lot of money out there."