Britain has become the online "designer drugs" capital of Europe with more than a third of all internet retailers that sell "legal highs" based in the UK...

This new generation of online "head shops" is at the centre of a rapidly growing market in highly potent synthetic drugs, such as Spice, that mimic the effects of illegal substances such as cannabis and ecstasy.

Paul Griffiths, of the European drugs agency, said that Spice contained a new compound, JWH-018, which was the first synthetic cannabinoid the active ingredient in marijuana and which was very potent even at low doses. In the face of the growing crackdown on Spice, research chemists have already developed a range of nine other cannabis-like drugs that would not be covered by the ban.