The BBC's Health Correspondent James Westhead: "Increasing numbers of doctors are frustrated"

The British Medical Association says it will advise all doctors to continue to prescribe the controversial impotence drug - unless guidance is published in the next two weeks.

Currently, the tablets are available privately, costing £12 each.

But politicians fear that being able to obtain a whole bottle of the drug for the standard prescription fee could cost the health service £1bn a year.

They also fear a black market in the diamond-shaped blue tablets may flourish.

Mr Roger Kirby: "Ridiculous paper chase"

The Chairman of the Patients' Association and former Agony Aunt Claire Rayner says people should not see the drug as a right.

She said: "What worries me is that people will think they have a God-given right to always be right at the top of the virility level.

"That is not realistic and that is the message I am trying to get across to people.

"Provide it for those whose need is deeply and undoubtedly medical/surgical - for the rest of us let's keep a bit of common sense about this."

Roger Kirby, consultant urologist at London's St George's Hospital, which sees 50 patients a month with erectile problems, describes the present situation as "chaos".

He said: "We have chaos right now, total chaos. Some GPs are regarding every patient as being exceptional and giving it [Viagra] to everyone.

"Some GPs are regarding the guidelines from the government that the drug is so-called blacklisted, so they are not giving it to anyone.

"We have a ridiculous paper chase over a drug which costs £4.86 a tablet."