Health chiefs have warned of further surgery cancellations across Northern Ireland as staff are diverted to treat increasing numbers of Covid-19 patients in intensive care.

The Health and Social Care Board said action was needed to increase ICU capacity in hospitals across the region and the only way to achieve that was to redeploy specialist staff working in other areas of the healthcare system.

The board also expressed concern at increasing numbers of unvaccinated young people and pregnant women being admitted to hospital with Covid-19.

It said there had been instances of unvaccinated pregnant women needing ICU care and emergency caesarean sections.

The board said that of all Covid-19 patients in ICU on Thursday, 60% were not vaccinated and 13% only had received one jab.

Hundreds of procedures have been cancelled in recent weeks, including some urgent cancer surgeries, due to the pressure on the system.

Paul Cavanagh, the interim director of planning and commissioning with the board, said he was not optimistic that the pressures would relent until after winter.

He said further cancellations next week were unavoidable.

"That will be incredibly frustrating for patients and I fully accept that and we can only apologise for it," he said.

"It's very challenging. It depends as much on just how many more critical care patients come into our system.

"We've seen an increase in recent days - we've seen a recent increase as well in our respiratory patients and those respiratory patients are an indicator of some of whom will require critical care as well in the coming days.

"It's a changing picture. But I think there will be further cancellations and we'll do our best to limit that as much as we possibly can, but our expectation is we will not be able to prevent it completely and there will be further cancellation of operations next week."

Mr Cavanagh said there was no immediate plan to stand up Northern Ireland's region wide Nightingale ICU Covid hospital at Belfast City Hospital.

He said trusts were instead attempting to escalate capacity within each of their areas, so the pressures could be spread throughout the region.

ICU consultant Dr George Gardiner described the situation in intensive care wards.

"We are seeing a different presentation of critically ill patients, those that pass through the wards and deteriorate and come to intensive care are younger, much younger and often without anything else wrong with them," he said.

"So if there was a perception in previous times that this was a disease of older people or sicker people, then the virus has changed or simply now we've only got younger people left to infect."

He said staff were upset and stressed at being unable to do planned surgeries.

"It's going to affect and is affecting elective surgery and all elective procedures and urgent procedures," he said of the influx of Covid-19 patients.

"In order to cope with the level of demand we are having to stress the system to the limit and we may have to go beyond that.

"The one thing that could modify this is for those people who have not yet taken a vaccine to do that. This is not a big ask. It's not a lifestyle changing modification, it's a simple attendance to get a vaccine.

"From what we're seeing in intensive care, this is not a disease that you want to expose yourself to unnecessarily. Our patients are not getting better quickly."

Critical care nurse Anne Marie Marley said she had never seen so many young people in ICU.

"This time around it's very different, it's like something I have never seen in 35 years of my career, where we are having really young patients coming in, not necessarily with any pre-existing conditions," she said.

"When you see kids coming in, 18 years (of age) in and around, people who are 30, people younger than me coming in requiring this very high level of intervention and care. They are absolutely terrified. It is so upsetting for staff to have to witness."

The pressure on the system has been exacerbated by the numbers of staff off work for Covid-19 reasons, the majority of whom having to self-isolate after coming into contact with a positive case.