If I choose - once I have fulfilled all my time obligations to the NHS, to go off and run a flower shop, work in the private sector, or just sit in front of the television - then that, quite frankly, is none of the NHS's business

Dr Michael Goodman, BMA

More consultants would also be eligible for access to an expanded clinical awards scheme to replace the merit awards system that allows doctors to top up their basic pay.

Announcing the proposals, Mr Milburn said: "Under these plans NHS patients will get the full benefit of senior doctors' unrivalled skills while the hard work of NHS consultants will be better rewarded.

"Since 1948 the whole assumption in the NHS has been that the only way for consultants to get on is by doing more private work.

"That cannot be right either for NHS consultants or for NHS patients.

"These proposals will provide a clear career structure for consultants and more incentives for doing NHS work."

Extra work

At present, consultants are allowed to carry out extra private work provided they have completed enough work for the NHS.

They forfeit a small amount of their NHS pay as a result - but can boost their earnings considerably by private work.

But the government sees restricting this right as a way of diverting more manpower into treating NHS patients.

Last year it threatened to stop newly-qualified specialist doctors being paid at full consultant rates if the profession does not co-operate with the contract changes.

However, leading doctors at the British Medical Association (BMA), already furious that the government has so far avoided any negotiation on these issues, are unlikely to give in over restrictions to their private work.

They see any attempt to control what doctors do in their own free time after NHS work as an infringement of their basic rights.

Dr Michael Goodman, a member of the BMA's consultants' committee, said: "We don't see why young consultants should be picked on in this way.

"If I choose - once I have fulfilled all my time obligations to the NHS, to go off and run a flower shop, work in the private sector, or just sit in front of the television - then that, quite frankly, is none of the NHS's business.

"Provided it does not interfere with my work for the NHS, there is no problem."

'Sensible negotiations'

Dr Peter Hawker, chairman of the committee, told the BBC he wanted "sensible negotiations" with the government - and clarification of the exact meaning of the NHS Plan.

If you look at our longest waiting lists, areas like orthopaedics and ear, nose and throat, they are exactly the areas where you have got the highest private earnings

Professor Julian Le Grand, London School of Economics

He said: "If it says exclusively for the NHS then no consultant could appear as expert witness in a court case.

"I'm trying to find out what they are actually aiming to do. I suspect the government has finally realised they are getting consultants on the cheap."

The government is already planning a "concordat" with the private sector, so that spare capacity in independent hospitals can be used by the NHS in times of great pressure.

Professor Julian Le Grand, of the London School of Economics, told the BBC that the problem of private work had to be addressed.

He said: "If you look at our longest waiting lists, areas like orthopaedics and ear, nose and throat, they are exactly the areas where you have got the highest private earnings.

"The average orthopaedic surgeon spends just seven hours in the NHS per week operating."

Shadow health secretary Dr Liam Fox said a Tory government would reverse any ban on consultants carrying out private work.

"This policy smacks of the centralising, authoritarian tendency of a Secretary of State who increasingly wants to control the whole of the NHS from behind his desk in Whitehall."

Nick Harvey, for the Liberal Democrats, said: "Until the number of doctors going through training is at a higher level or more doctors are recruited from overseas, it is of course desirable to maximise consultants' work for the NHS. But �10,000 will not begin to compensate consultants for what they will to lose."

Negotiations on a final contract for consultants may not be completed until next year.