Writing in the British Medical Journal, Professor Rudolf Klein, from the independent health watchdog, the King's Fund, calls on ministers to acknowledge that setting priorities in health care is inescapably a political process.

Professor Klein argues that Health Secretary Frank Dobson will only make himself "look foolish and undermine his credibility" if he continues to ban the word rationing from the ministerial vocabulary.

He writes that once the inevitability of rationing is finally accepted "we can get down to the serious business of discussing how to devise the appropriate mechanisms ... involved".

Professor Klein argues that a National Council for Health Care Priorities would provide a forum and a focus for the rationing debate in the UK.

Rationing decisions, Professor Klein argues, must be able to stand up to public scrutiny. They must be seen to be relevant and fair, even if most people would not agree with the decision to ban treatment.

'Messy and difficult'

However, he writes: "Grappling with the problem of how to reconcile growing demands and constrained resources is ... inevitably messy and difficult.

"The challenge everywhere is about how to organise and orchestrate what, for the foreseeable future, will be a continuing dialogue between politicians, professionals, and the public about the principles that should be invoked in making decisions about rationing and about how best to reconcile conflicting values and competing claims."

Viagra has been banned from the NHS

Professor Klein says arguments over rationing tend to focus on whether a specific treatment should be limited or banned.

However, the most common form of rationing was a dilution of services, such as a reduction in the time doctors can spend with patients, and in the number and quality of nurses on the ward.

A decision also had to be taken about whether to impose explicit national guidelines or to give more discretion to clinicians when faced with individual patients.

Professor Klein writes: "In the absence of discretion, injustice may be done to individuals. Yet too much use of discretion may subvert national policy: medical necessity is a flexible concept."

Labour's denial 'incredible'

Shadow Health Secretary Ann Widdecombe rounded on Mr Dobson at the Conservative Party for his failure to accept NHS rationing was inevitable.

She said: "I know it's almost too incredible to believe, but Labour's White Paper actually said 'we don't find the arguments in favour of rationing to be convincing'.

"Astonishing, isn't it? But you've got to feel a little bit sorry for Frank. After all, if he doesn't know how many hospitals he is personally closing down, it's not too hard to believe that he's in blissful ignorance of something that's been part of our health service for the last 50 years.

"He doesn't seem to realise that he is making rationing decisions every day. You can't get operations for varicose veins, lipomas, or sebaceous cysts any more in our health service on a national basis."