Video report by ITV Political Correspondent Libby Wiener
Health Secretary Jeremy Hunt has apologised after winter pressure on the NHS forced tens of thousands of planned operations in England to be postponed.
He told ITV News it was "unacceptable" for patients to face additional pain because of the cancellations that aim to free up hospital staff and beds.
Prime Minister Theresa May and NHS chiefs have also denied hospitals in England are in crisis after under-pressure wards were instructed to delay pre-planned ops and routine outpatient appointments for several weeks.
Their claims of being "better prepared" for the winter demands have been questioned by the Royal Collage of Emergency Medicine, who said: "We note the influence of the flu, norovirus and cold weather (on the NHS), all of which were predicted."
The strain in England's hospitals came as new figures out Wednesday showed a slight decline in the number of cancellations of planned operations in NHS Scotland.
Apologetic Hunt defends NHS planning and funding
The health secretary told ITV News the seasonal pressure was predicted and echoed NHS chiefs in saying hospitals had been "better prepared" for this year's conditions.
But he said: "That doesn't mean there isn't huge pressure."
When asked if he would apologise to patients, he said: "Of course".
Mr Hunt added: "If yours was the hip replacement that was cancelled and you could have to wait another month for that you could be in pain and that is unacceptable and I apologise wholeheartedly for that."
He rejected claims a lack of investment had left departments understaffed, saying a "significant amount (of funding) for the NHS" had made a "significant difference" in the service.
The government invested an additional £437 million this year along with £1 billion extra social care funding.
How big is the scale of the winter pressure?
Leading medics have warned every emergency department in the country is struggling to cope with winter pressures.
Some hospitals have declared themselves at the most severe pressure level while ambulance services have also expressed severe concern, with some even resorting to taxis to ferry patients to hospital.
The deferral of non-urgent inpatient elective care - such as hip replacements - should be extended until January 31, but cancer operations and time-critical procedures are not expected to be affected.
What measures are being taken?
Under-pressure hospitals have been given permission to reduce the non-urgent care "in a planned way".
However, the hospitals have been told to avoid last minute cancellations of operations.
Hospitals have been told to accept they may have to have mixed sex wards if that becomes necessary.
Hospitals must defer some of the routine outpatient work.
Free senior specialists will be made available to GPs to assess patients.
Therapists will be freed up to help prepare patients to go home safely from hospital.
NHS England hopes the steps will free up senior hospital doctors to triage more patients in A&E, be available for phone advice for GPs and ensure patients in hospitals are reviewed twice each day to help timely discharges.
The measures were announced following a meeting of its National Emergency Pressures Panel (NEPP).
NHS England said the panel discussed "sustained pressure over the Christmas period" with high levels of respiratory illness, high bed occupancy levels, signs of increased flu activity and a rise in the number of severe cases attending A&E.
Should extra winter demands have been better anticipated?
The Royal College of Emergency Medicine criticised the NHS's handling of what it said were anticipated winter demands.
"We note the influence of the flu, norovirus and cold weather all of which were predicted," it said.
"The long-predicted worsening in performance of care delivery in our Emergency Departments comes on a background of a chronic downward performance spiral to a point where safety is a serious concern for an increasing number of departments.
"The suggestions made by the NEPP are helpful. However, good hospital systems are doing much of this already."
May defends NHS investment as Labour attack 'underfunding'
The prime minister described the delays as "disappointing" and "frustrating" for patients awaiting treatment and said: "We will ensure that those operations are put back as soon as possible."
Mrs May also defended the government's investment, saying: ''There are more beds available across the system, we've reduced the number of delayed discharges of elderly people who would otherwise have been in NHS beds rather than in social care."
Labour's shadow health secretary Jonathan Ashworth criticised Mrs May as "entirely out of touch" and called on her to "explain why she has allowed underfunding and cuts to health and social care to continue."
He added: "As Tory MP Sarah Wollaston said this morning, the Government needs to get a grip."
NHS chief: 'We're more prepared than we've ever been'
NHS England's medical director for acute care rejected any claims of a crisis in the service after some doctors lambasted "third-world care" on some under-pressure wards.
Professor Keith Willett insisted the service was able to deal with the overload of winter cases, saying: "We're more prepared than we've ever been."
"The NHS always has difficulty in the first few weeks of the new year. That's when pressures are highest," he said.
"So we have taken steps ahead of dealing with that pressure to manage things this year."
What do the latest figures reveal about NHS Scotland?
Video report by ITV News Scotland Correspondent Peter Smith
NHS Scotland has also faced claims of a winter crisis amid a surge of winter cases.
ITV News Scotland Correspondent Peter Smith said the latest figures on operation cancellations and A&E waiting times in late 2017 showed an improvement on the same period in 2016.
But one Scottish health board has been forced to redeploy office staff and postpone some non-urgent procedures to cope with soaring demand.
NHS Lanarkshire said its three hospital sites had been "inundated" with over the festive period and that "exceptional measures" were necessary.
Some office workers have even volunteered to take on administrative and cleaning roles over the next few days to ease the burden.
Ambulance hours 'lost' due to delays at Welsh hospitals
Delays at Welsh hospitals have lead to around 2,000 ambulance hours being lost over the past seven days, ITV Wales understands.
Video report by ITV News correspondent Emily Morgan
The Royal College of Emergency Medicine described the situation as "dire" and "horrific".
A Welsh Government spokesperson said: “Winter and the period immediately after the new year bank holiday is always a challenging time for our health service, as it is across the UK, and we have been working with health boards and partners to ensure the NHS is prepared.
"This includes increasing capacity, for example by strengthening emergency ambulatory care services and increasing the number of beds available when demand is high.”
The Welsh Ambulance Service said it saw a 170% increase in calls over the first four hours of New Year's Day compared to a normal day.
It said call handlers dealt with 721 calls between midnight and 4am, compared to the usual average of 267 calls in that time.
On Boxing Day, the service said it received nearly 1,600 calls – 300 more than usual.
Richard Lee, the Welsh Ambulance Service's director of operations, said they received 1,000 calls more than expected on New Year's Day.
Northern Ireland hospital using volunteers in A&E amid crisis
A nursing union has said using volunteers to help patients amid the crisis facing Northern Ireland’s health service is an unprecedented move – and "highly dangerous".
St John Ambulance workers were invited to Antrim Area Hospital on New Year’s Eve to help with patients waiting for emergency treatment.
The role was said to be largely limited to sitting with patients, making tea and keeping them company during their wait.
The volunteers also had to be accompanied by registered nurses.
But Janice Smyth, NI director of the Royal College of Nursing, said: “This is heading only in one direction and in the absence of a workforce plan this is highly dangerous.
“Once broken, it is not easily fixed.”
She added that there are 1,500 nursing vacancies waiting to be filled and that there was not enough staff to support the number of beds – let alone those waiting on trolleys during peak times.
According to health officials, a total of 15,626 patients were treated at Northern Ireland’s main Emergency Departments between Christmas Eve and New Year’s Day.
That represents an increase of 4% on last year and 14% on 2015/16.
A total of 928 had to wait longer than 12 hours to be seen, treated, and either discharged or admitted to hospital.