The makers of anti-impotence drug Viagra have withdrawn their bid to make it available without a prescription.

Drug company Pfizer had wanted to make 50 milligram tablets freely available in the European Union.

But in a letter to the European Medicines Agency (EMEA), Pfizer said it would withdraw the application in the light of concerns from EMEA's Committee for Medicinal Products for Human Use.

A spokeswoman for EMEA said: "One concern was that its use with a lack of proper medical supervision could delay diagnosis of the underlying causes of erectile dysfunction which can include heart disease."

Viagra, the marketing name of the drug sildenafil citrate, overcomes impotence by blocking an enzyme that limits blood flow to the penis.

Rory O'Connor, Pfizer's vice president of Medical and Regulatory Affairs, said: "Sildenafil citrate has a proven safety profile that has been well established in extensive post-marketing studies and in more than 120 clinical trials.

"We will continue to work with regulators in Europe to improve the availability of our medicines to patients and physicians and the benefits they get from our therapies."