Contingency measures are being put in place to ensure that a full service will be provided at St Colmcille's Hospital at Loughlinstown, Co Dublin, when industrial action by four theatre nurses resumes this afternoon.
The East Coast Area Health Board said last night that the accident and emergency department will remain open.
But ambulances will be diverted to nearby hospitals at night until the Irish Nurses Organisation (INO) re-enters negotiations, the health board spokesman said.
The INO represents the four theatre nurses taking strike action over the level of "on call" cover provided at the hospital. The industrial action, which resumes today after the breakdown of talks at the Labour Relations Commission earlier this month, has resulted in a lack of cover in operating theatres at night.
The INO says the industrial action centres on the fact that job-sharing theatre nurses are providing double the rate of "on-call" cover provided by their full-time colleagues.
The health board, however, says the union has ignored the usual industrial relations procedures to resolve the matter.
A spokesman for the ECAHB said the health board management was "surprised and disappointed" when the INO served notice of their intention to strike.
Ambulances have been diverted to other hospitals at certain times in the past during the dispute due to the resulting staffing problem in operating theatres, said the health board.
The parties are now seeking an early hearing at the Labour Court following their failure to reach agreement on the issues in talks earlier this month.