NHS managers have described a plan to extend the EU working- time directive to junior doctors' hours as 'unworkable' .
Last week, the European parliament voted in favour of including junior doctors in the directive, initially with an upper limit of 54 hours a week, to be phased in over four years.
But the NHS Confederation said it wanted to see a 13-year lead-in to ensure that the first wave of 1,000 extra doctors entering medical school was suitably qualified before starting work on the wards.
Human resources chair Andrew Foster said it would not be possible to implement any more cuts in doctors' hours without more staff.
'You can do a bit of tinkering at the edges to get from 83 down to 56 hours, but you can only go so far with existing numbers.
'The first batch of 1,000 extra doctors is still seven years off, the first extra batch of senior house officers eight or nine years off and registrars 11 or 12.
That is why we favour a 13-year period of assimilation and not four years like the British Medical Association.'
He added: 'There is an awful long way to go yet. The decision has to go back to the Council of Ministers.'
Dr Ian Wilson, head of the UK delegation on the permanent working group of European doctors, a Europewide forum for the medical profession, agreed that implementing the recommendation in full would require an extra 6,000 doctors.
'It would be best for patients if most of the required new posts were fully trained consultants and GPs and not simply more junior doctors, ' he said.
But he added that patients had a right to speedy protection from overworked doctors.
'Thirteen years is far too long to ensure that patients are legally protected from junior doctors working dangerously long hours.
'This sends a clear message to the Council of Ministers and we urge them to act on this vote. We hope that the final decision will result in a favourable and realistic outcome.'
The government has pledged to oppose the four-year plan. Even if it is backed by the Council of Ministers the government has not ruled out seeking derogation - a special dispensation exempting the UK for a fixed period.
The Department of Health has told English junior doctors that, unlike their colleagues in Scotland, they will get no national agreement on millennium pay.
The BMA's junior doctors committee said junior doctors working in England will work for as little as£4.02 an hour over the holiday when other staff are earning double or, in some cases, triple time.