All five Northern Ireland health trusts have cancelled non-urgent operations due to pressures – particularly on accident and emergency departments.
The unusual measure was introduced after the trusts reported an exceptionally busy weekend right across Northern Ireland.
The South Eastern Trust said it is experiencing “significant pressure at all our emergency departments, and increasing emergency admissions to all our hospitals”.
It added: “We are facing particular challenges at the Ulster Hospital emergency department, and would like to remind people to only attend if they are a genuine emergency.
“Patients may have to wait longer than usual because of the surge in attendances.”
Belfast Health Trust has cancelled all non-urgent surgery up to Saturday.
“This decision has not been taken lightly and will be kept under review throughout the remainder of the week,” a spokesperson said.
“We would like to stress that cancer surgery and emergency cases are unaffected.
“Minor healthcare issues can be dealt with at home, by a pharmacist or by a GP.”
The Southern Trust told the BBC it had cancelled less than 10 operations but was only doing so yesterday.
Sinn Fein MP Paul Maskey has requested a meeting with the new chief executive of Belfast Health Trust, Dr Michael McBride.
“One of the issues I will be raising as a priority is accident and emergency provision in Belfast and at the Royal Hospital in particular,” he said.
“In the past few weeks we have again seen the department being swamped to a point where people were left on trolleys for over 12 hours.”
Despite repeated declarations of major incidents, there was “a spike” in waiting times at the weekend, he said.
Sinn Fein health spokesperson in the Republic Caoimhghin O Caolain yesterday demanded urgent action, saying 601 patients are being cared for on trolleys across the Republic.
Prime Minister David Cameron yesterday admitted the NHS is under “pressure” after waiting times in English emergency departments plummeted to their worst levels in more than a decade; just 92.6 per cent of patients were seen within four hours – notably below the 95 per cent target.
Mr Cameron said a lot of the pressure on emergency departments comes from frail, elderly people.