A report from the national Aids charity, Crusaid, showed only half of specialist doctors consistently prescribed up-to-date, triple-drug therapy for patients with mid-stage HIV infection.

Of those specialists who had seen patients with late-stage infection, 15% had not provided triple-therapy.

Nearly a third of specialists had recommended at least once that a patient seek treatment outside their health authority.

The results were obtained from a Mori telephone survey of 110 HIV specialist physicians in the UK.

Sub-standard treatment

Crusaid chief executive and biologist, Dr James Deutsch, warned that sub-standard treatment could promote the development of drug-resistant HIV.

He said: "The results of this study are a real cause for concern because we know that ineffective HIV treatment causes the evolution of drug-resistant `super-HIV' which can then be transmitted to new patients.

"Only by providing patients across the country with up-to-date, effective treatment can we stop the development of a new epidemic, resistant to the current drugs."

Dr Mike Youle, HIV specialist at the Chelsea and Westminster Hospital and Royal Free Hospital, London, said: "The findings of this study clearly show that there are variations in access to therapeutic options across the UK and that these depend, to a degree, on the patient's postcode.

"There are worrying indications of the fairly widespread use of low-strength combinations which, if inappropriately used, may compromise future therapy choices."

Smaller clinics at fault

He said the problem of ineffective treatment was particularly pronounced in smaller clinics.

The main reason given by doctors for recommending treatment elsewhere was to allow patients access to clinical programmes they could not provide.

Six per cent of doctors said they had made the recommendation because they felt patients would benefit from others with more experience. Restraints on funding were also mentioned by 6%.