Northern Ireland's health trusts are under severe pressure as an unprecedented number of people have been seeking treatment at emergency departments.
Some 250 people waited at Craigavon Area Hospital over the last two nights for assessment, said SDLP MLA Dolores Kelly.
Antrim Area Hospital is also affected.
Sean McGovern from the Royal College of Emergency Medicine NI said the situation was the worst he has seen.
"The situation is in crisis," he said. "We have an extraordinary number of people waiting for a bed.
"We have a social care system that requires reform and we have staffing depletion."
Health and Social Care Board figures
From 24 December to 1 January - 15,626 patients were treated in emergency departments
That is an increase of 4% on the same period last year.
Of those, 3,500 were admitted.
Some 928 patients waited more than 12 hours for admission, transfer or discharge.
On the morning of 3 January, 186 men and women were waiting for a hospital bed.
The medical director of the Northern Health Trust said the severe pressure on emergency departments this winter is an issue with capacity, rather than performance.
Seamus O'Reilly, who also represents the Health and Social Care Board, said the demand for emergency department services from elderly patients has been greater than expected. He said that leadership from Stormont is needed.
"The civil servants are already moving forward on transformation of the health and social care system in Northern Ireland," he said.
"But yes, if the politicians were in Stormont and if we had a health minister then we could move that forward at a pace."
Ms Kelly said she had been speaking directly to trade union representatives and some staff who were "very concerned" at the number of people waiting to be seen in the emergency department at Craigavon Area Hospital.
'Scene of chaos'
"On Tuesday evening at 19:00 there were 108 people waiting to be assessed in the emergency department, while on Monday night there were over 140 people," she said.
"Some people had to wait over seven hours to see a doctor, it was a scene of chaos.
"People are queued right back to the shop in the foyer with standing room only.
"People lying on the floors being sick, just absolute distress and a stressful situation for staff."
In a statement, the Southern Health Trust said its emergency departments remain "extremely busy" and that the most urgent cases are being prioritised.
The BBC understands some health trusts are advising staff not to book certain "non red-flag or emergency operations in advance" as hospital beds are in short supply.
Dr Tom Black, chairman of the BMA's Northern Ireland general practitioners committee, told the BBC on Wednesday that 50%-60% of out-of-hours GP shifts go unfilled.
On Tuesday, the Irish News reported that managers at Antrim Area Hospital had to call in St John Ambulance volunteers to provide basic ward cover on New Year's Eve.
The hospital's director of nursing "did not make the decision lightly", said the Northern Ireland Director of the Royal College of Nursing, Janice Smyth.
"It was probably the least worst option," she told BBC NI's Good Morning Ulster.
"It is just a sign of further deterioration within the health and social care system here".
She said the nursing profession in Northern Ireland was "very disillusioned" that it had been left in this position.
"It was through sheer desperation that decision was made."
Ms Smyth said a lack of hospital beds and nurses in Northern Ireland would have an impact on planned surgery and treatments for "the next number of weeks".
The Northern Health Trust told the Irish News the decision at Antrim Area Hospital had been made as a "direct response to the high numbers of patients in the emergency department and was most welcomed by staff".
It said the number of patients attending its emergency departments this winter has been "unprecedented".
The trust runs several hospitals, including the Ulster Hospital in Dundonald, County Down, and the Lagan Valley Hospital in Lisburn, County Antrim.
Last week, Londonderry's Altnagelvin Hospital in the Western Health Trust implemented an emergency plan to cope with the number of patients with which it was dealing.
On 26 December, doctors in the Southern Health Trust said patients were having to wait for up to 34 hours to speak to an out-of-hours GP.