The Emergency Department at Belfast City Hospital has been closed today because of a shortage of senior doctors.
Up to 40,000 patients attend the department there annually and are now being asked to go to the nearby Royal Victoria Hospital instead.
The department was initially due to close in October, but the move was delayed due to concerns about the impact the closure would have on other hospitals.
Health officials said the closure will be temporary, however the Belfast Health and Social Care Trust has not given a guarantee that the unit will re-open.
