The health service will have to appoint significant numbers of additional doctors and re-configure existing hospital services in some areas if it is to achieve compliance with European rules governing working hours for medical staff.

An opinion published on Thursday by the advocate general at the European Court of Justice maintained that Ireland was in breach of the EU’s working time directive in relation to the working hours of non-consultant doctors.

If this opinion is upheld by the European Court of Justice in a ruling due later this year, Ireland could face significant fines.

The Irish Medical Organisation (IMO) said the fines could be up to €100 million, while the State could also face further penalities of up to €1 million per day applied if the breach of the directive continued.

The advocate general opinion said that by excluding the training hours of non-consultant hospital doctors from the concept of “working time,” the State was in breach of European law.

While the opinion by the advocate general is not the final judgment, in the vast majority of cases the Court upholds the opinion.

Under current arrangements, the work of non-consultant doctors in public hospitals is divided between the time spent treating patients and protected time for training.

The opinion stated that workers were entitled to a minimum rest period, and Ireland’s decision to exclude training time from the calculation of doctors’ working time “encroaches on that minimum rest period”.

“Contrary . . . to the impression that Ireland wishes to convey, the two aspects of the activity performed by non-consultant hospital doctors - their provision of medical care and their training - are intrinsically linked,” the opinion states.

The Minister for Health Leo Varadkar said Ireland was committed to the full implementation of the working time directive. He said while good progress had been made, he acknowledged this had not yet been fully achieved. He said an additional 400 non-consultant doctors had been recruited in the last 2 years and the health service was close to eliminating the requirement for doctors to work shifts of longer than 24 hours.

However he warned that “reducing average working times to 48 hours or less per week remained a challenge, particularly in smaller hospitals”.

He also said that attainment of compliance with the directive would require reconfiguration of some services.

Eric Young, IMO assistant director of industrial relations, said there were still 230 non-consultant hospital doctors in over 21 hospitals working more than 24 hours. He said some were forced to work 32-hour shifts.