Prague  - Czech authorities raided a methamphetamine lab, arresting two Britons and three Czechs suspected of producing and smuggling the drug for use in Britain, police said Friday.

Police allege that the Czechs brewed up to half a kilogram of the highly pure drug commonly known as meth a week at their Prague lab and that the Britons - arrested at the capital's airport - provided the money and brought the illegal stimulant to Britain.

Meth has become the Czech Republic's signature illicit drug racket. After communism fell in 1989, the powerful stimulant began spreading, first to neighbouring Germany, then elsewhere.

"Methamphetamine is a growing problem," narcotics police spokesman Bretislav Brejcha said.

Police said the Czech suspects went to pharmacies to buy common over-the-counter cold medicine containing pseudoephedrine, the key ingredient in meth.

Some 80 per cent of pseudoephedrine-containing cold medications sold in the Czech Republic are cooked into meth, according to official estimates. But the government is not expected to restrict sales before 2009.

If convicted, each suspect could face up to 15 years in prison.