One in four hospitals are unlikely to be able to cut junior doctors' hours sufficiently to meet new European rules, a survey has found.
The directive comes into force in August
The European Working Time Directive, to be implemented from August, limits junior doctors' hours.
However, the survey, by the Royal College of Physicians, found 23% of hospitals in England and Wales will struggle to meet the new rules.
Many trainee doctors currently work much longer hours.
Staff shortages mean that many hospitals do not have the ability to cut back.
The problem lies, not with the total number of hours worked, but with rulings on the amount of rest doctors should have between shifts.
It has been ruled that doctors should have 11 hours of rest after working a 13 hour shift.
The RCP says there are not enough doctors to allow that to happen in just under a quarter of hospitals.
They estimate each hospital needs a "cell" of 10 junior doctors working 13-hour full shifts to provide safe and effective 24-hour cover for one post.
But there are fears that many doctors will be upset at the prospect of doing full nightshifts for up seven days in a row.
Lack of experience
Dr Hugh Mather, specialist registrar adviser at the RCP, said: "This survey shows that a significant number of hospitals still have insufficient experienced middle-grade staff to comply fully with the EWTD in acute medicine.
"The situation is worse in paediatrics and obstetrics."
Dr Mather said two judgments made in the European Court ruling that time spent
sleeping on call should count as working time were "proving to be unrealistic
and very damaging".
"We welcome the recent statement from the Government and the European
Commission that they intend to review the implications of these judgments during
"Unless they are remedied, the maintenance of safe levels of acute patient
care will become very difficult in some hospitals."
Professor Roy Pounder, RCP vice-president, said: "It is strange that regulations to improve the lives of workers would force most junior doctors to work seven consecutive 13-hour night shifts without a break.
"The majority of junior doctors in the NHS already work less than 58 hours a week under the New Deal, but it is the precise details of the Directive and the European Court judgments that make the situation extremely difficult.
"France, Germany and the Netherlands are in similar difficulties, and it is imperative the European Commission introduces new regulations without delay."
Earlier this month a House of Lords committee warned that hospitals were facing a major staffing crisis as a result of the European legislation and court rulings on doctors' working hours.
The Lords' European Union committee cautioned that the extension of the EWTD to junior hospital doctors, combined with the two judgments, could have a
dramatic effect on the NHS.
Committee chairman Lord Williamson of Horton said they had been told that the effect would be "tantamount to losing the equivalent of 3,700 junior doctors".
Health minister John Hutton said: "The NHS is making progress in preparing for implementation of the directive in August and 95% of doctors in training are
actively working for 56 hours or less.
"The limit is 58 hours, but recent court rulings have made implementation more difficult.
"We are continuing to take every measure to ensure that we comply with the directive while maintaining NHS services to patients."
Shadow Health and Education Secretary Tim Yeo said the survey added to his concerns about the potential effect of the working time directive.
He added: "With only four months to go until the directive comes into force, it is alarming that there are so many unanswered questions."