Health Secretary Frank Dobson has increased the number of men who will be able to receive impotence drug Viagra on the NHS.

But, at the same time, he has restricted NHS access to other impotence treatments.

Doctors have given the decision a cautious welcome, saying some men with a clinical need for Viagra may still be "arbitrarily" denied it.

NHS managers say it is a "sensible and fair" decision.

The government's announcement follows interim guidance issued in January that Viagra would be restricted to certain groups of patients.

Doctors criticised this as being "unfair" and "irrational" and the British Medical Association (BMA) advised members to disobey the advice.

The guidance was subject to consultation with health workers.

The government says it has received 861 responses and has decided as a result to increase the number of patients who will get the drug.

In January, the drug was limited to people with diabetes, multiple sclerosis or other single gene neurological diseases that cause impotence, spinal cord injuries, those who have undergone radical pelvic surgery and those had had their prostate gland removed.

Men who were in severe distress because of impotence were also able to have the drug on the NHS if a hospital specialist recommended it.

New rules

Under the new guidelines, the following men will also qualify for the drug on the NHS:

• Men treated for prostate cancer
• Men treated for kidney failure, by transplantation and dialysis
• Men who have had polio
• Men with spina bifida
• Men with Parkinson's disease
• Men with severe pelvic injury

Men who were receiving impotence treatments on the NHS before 14 September 1998 will also qualify.

Mr Dobson said GPs should be restricted to prescribing one pill a week.

The restrictions on Viagra apply to all other impotence treatments.

Mr Dobson justified the restrictions on the grounds that the cost of making it widely available could not be justified in terms of his duties to the NHS as a whole.

Viagra now becomes only the seventh drug to be restricted for this reason under Schedule 11 of NHS (General Medical Services) Regulations issued in 1992.

GPs will be able to write private prescriptions for Viagra for their patients.

The proposals will come into effect on 1 July, subject to parliamentary approval, and will be reviewed in a year's time.

Mr Dobson said three quarters of the 861 replies he had received supported restrictions on NHS availability of Viagra.

Ten per cent wanted the drug to be banned altogether, he said.

And over half said other impotence treatments should be similarly restricted or banned.

Mr Dobson said he had to find "a sensible balance between treating men with the distressing condition of impotence, and protecting the resources of the NHS to deal with other patients".

NHS managers had warned widespread access to the drug would cost the government �100m a year.

The change in guidelines is expected to raise the cost of NHS Viagra from �12m a year to �14m.

Rationing

The debate over Viagra has highlighted the issue of NHS rationing.

Doctors and campaigning groups claimed the January restrictions meant only 15% of impotent patients would be eligible for Viagra on the NHS.

They said the other 85% would have to buy the tablets privately, at a cost of �12 each. The NHS can buy the drug for �4.86 per tablet.

The drug's manufacturer, Pfizer, this week announced that it was suing the government over guidance issued in September when the drug was approved for use in European Union countries.

The government told doctors not to prescribe Viagra until further notice - unless there were exceptional circumstances.

Pfizer says this was illegal. It is estimated that one in 10 men in the UK suffers from impotence.