The Russian Health Ministry has announced that the impotence treatment Viagra will go on sale in Russian pharmacies from the autumn.

Russian NTV television said this had been confirmed by the US manufacturers, Pfizer.

It will make Russia the fifth country where Viagra is legally on sale.

The television reported that Viagra was being legalised to counter the fact that it has become the most popular drug on the medical black market in Moscow.

Ramil Khabriyev, the head of the Health Ministry's Medicinal Supervisory Directorate, said there was "an almost 100%" chance that customers were not buying the real thing.

Mr Khabriyev denied that legalisation had been rushed through to meet the demands of members of the Russian leadership.

"Everything's fine with the government, we've had no instructions from above to obtain Viagra or get it legalised quickly.

I don't think our leaders need the stuff, touch wood," he said.

Legal Viagra will be on sale only with doctors' prescriptions and will cost about 12 US dollars.

As a prescription drug it is banned it from being advertised.