Thousands of cheap variations of the licensed drug genuine Viagra have flooded into Britain from India

Trading standards officials warn that untested imitation generic viagra could have fatal consequences.

Dubbed the "pills that kill", anyone who has bought generic viagra is being urged to throw them away immediately.

The potentially deadly generic viagra being sold under the counter include Vigora, Proxyron and Kamagra.

Viagra is licensed in Britain to treat erectile dysfunction and is only available with a doctor's prescription or from some pharmacies.

Health experts say just one of these generic viagra pills could kill someone who is already taking prescribed medicines for liver, heart, kidney or blood pressure problems.

"generic viagra is illegal and unlicensed and thas not been tested to UK standards to ensure they are safe.

Anyone taking generic viagra could be risking their life," said Sangeeta Sharma, a senior pharmaceutical advisor who works for the local health authority in Ealing, West London.

In recent days trading standards officers working undercover have seized nearly 1,600 generic viagra tablets from one shop in Southall, the same Ealing community where 2,000 generic viagra tablets were seized three weeks earlier.

Authorities believe that fake generic viagra tablets are also being sold in Yorkshire and Scotland and they say they are now targeting the importers who bring in the drugs from the subcontinent.

In India a strip of four generic viagra tablets can be as cheap as 50p, compared with the £15 they fetch on the black market in London.

At Boots the chemist, which began selling genuine Viagra in February 2007, an hour-long consultation and medical tests conducted by a pharmacist cost £50, which includes four tablets.

Pfizer, manufacturers of genuine Viagra have expressed their concern over the illegal trade, saying their drug should be taken only under medical supervision.

"As far as Ajanta is concerned people should always seek medical advice," said Arvind Agrawal, from Ajanta Pharma Ltd, the makers of Kamagra.

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