Criminals are set to make millions of pounds selling the pills, which contain little or no Viagra, independent televisions ‘‘world in action programme reported.

‘‘Our research indicates that professional counterfeiters have turned their attention to Viagra, said Peter Lowe, assistant director of Britains counterfeit intellegence bureau.

Lowe said the fake versions of the drug, which are relatively easy to manufacture, contain either a below-strength active ingredient or none at all.

The illegal trade in Viagra, made by US drug firm Pfizer Inc, hit the headlines in Britain on Friday when police confiscated an illegal hoard being sold on the black market from an unlicenced sex shop in central London. Police seized around 60 pills.

The shop was charging 40 pounds for the diamond-shaped pill, which sells for afraction of that amount in the United States.