Almost 400 people were waiting for a hospital bed in Northern Ireland on Saturday afternoon, BBC News NI understands.
It is thought the majority of extra beds which are used in an emergency were already occupied.
Flu and respiratory infections have been affecting many people with some requiring hospital treatment.
BBC News NI also understands that 41 ambulances were queued outside Northern Ireland’s emergency departments at 15:00 GMT on Saturday.
One ambulance had been waiting outside a hospital for nine hours.There was not enough staff or space to facilitate crews or patients, it is understood.
A BBC reporter said at least seven ambulances were waiting to offload patients at Causeway Hospital in Coleraine on Saturday afternoon.
The Northern Ireland Ambulance Service (NIAS) said it was “experiencing severe challenges” as a result of the pressures being felt across the system.
“All calls received by NIAS are subject to triage to ensure that those who are sickest, receive our quickest response,” a statement said.
“This will unfortunately mean delays for patients waiting with less urgent conditions and NIAS would apologise to those patients who find themselves in this situation.”
Did the Department of Health’s winter preparedness plan published in early November go far enough?
Some of those currently working in the thick of it say it didn’t.One senior ED consultant told me that little had changed on the ground since November and things are likely to get worse.
Among the criticisms is that the winter plan doesn’t adequately address the basic issues which cause overcrowding and which delay people leaving hospital wards. The problem is not new.
The plan states there is capacity across all trusts to make over 300 more in-patient beds available when demand increases; however, some health professionals have told me that some of those 300-plus beds were already in use.
The plan included very basic alternative pathways such as pharmacy first, which staff have described as “meaningless” and a “drop in the ocean.
“A major part of the problem is there hasn’t been enough done to support people and staff in the community to prevent hospital admissions. This will take years to address, but it’s something NI has been discussing for over a decade.
Is general practice staffed and funded appropriately so the public can easily access? GP leaders have said it’s not.
Are nursing homes staffed sufficiently with enough GPs available to call out to avoid where possible older people having to be taken to hospital only to sit in an ambulance for hours?
Social care packages with skilled staff to support people at home are woefully inadequate. Again an age-old problem.
Many patients can’t be discharged as families won’t agree to the temporary recuperation facility as it isn’t located close enough to home.
NI’s winter planning involved roundtable discussions; however, some of those involved have said they were just that – discussions which lacked reasonable planning and action, both inside hospitals but more importantly in the community.
While preparing for winter is complicated, those on the inside have said the script will remain unchanged until there is a radical shake-up – the same applies across the UK.
BBC News NI contacted each of Northern Ireland’s health and social care trusts for comment about the hospital bed situation.
The Western Trust said that on Saturday afternoon, 70 people were awaiting beds across their trust area.
This number included 22 people at the South West Acute Hospital in Enniskillen and 48 people at Altnagelvin Hospital in Londonderry.
The Belfast Health Trust said its latest figures showed a total of 38 patients were waiting for admission to a hospital bed on Friday.
The Northern Trust said on X that it was “extremely busy today with long waits for those whose conditions are not life-threatening”.