The pressure on the NHS is "intolerable and unsustainable", medics have said, amid warnings that the deaths of up to 500 people each week could be caused by delays in emergency care.
It comes after more than a dozen NHS trusts and ambulance services declared critical incidents over the festive period, with officials citing rising flu cases and the impact of the COVID-19 pandemic among the reasons for the pressure on the health service.
Professor Phil Banfield, chair of British Medical Association (BMA) council, hit out at both the Prime Minister and the Health Secretary as he offered a stark warning about the scale of the crisis facing healthcare workers.
"The current situation in the NHS is intolerable and unsustainable, both for our patients and the hard-working staff desperately trying to keep up with incredibly high levels of demand," he said.
"The BMA has repeatedly invited the Government to sit down and talk about the pressures on our health service, but their silence is deafening.
"It is disingenuous for the Prime Minister to talk about 'backing the NHS' in his New Year message, when his own Health Secretary is failing to discuss how this crisis can be fixed."
He called on the Government to "step up and take immediate action" to solve the crisis.
The Royal College of Emergency Medicine also doubled down on its claim that somewhere between 300 and 500 people are dying each week as a result of delays and problems with urgent and emergency care, as it warned against any attempt to "discredit" the figure.
Ian Higginson, vice-president of the Royal College of Emergency Medicine, told BBC Radio 4's Today programme: "What we've been hearing over the last few days is that the current problems are all due to COVID or they're all due to flu, or that this is complex, you mustn't jump to conclusions – all that sort of stuff.
"If you're at the front line, you know that this is a longstanding problem. This isn't a short-term thing. The sort of things we're seeing happen every winter, and it still seems to come as a surprise to the NHS."
Last week, 1 in 5 ambulance patients in England waited more than an hour to be handed over to A&E teams.
NHS trusts have a target of 95% of ambulance handovers to be completed within 30 minutes, and 100% within 60 minutes.
In November, 37,837 patients waited more than 12 hours in A&E for a decision to be admitted to a hospital department, according to figures from NHS England.
This is an increase of almost 355% compared with the previous November, when the figure was 10,646.
Mr Higginson added that the Royal College of Emergency Medicine figures on deaths caused by delays were more than a "guesstimate".
"These are real figures and I worry that we're going to hear attempts to spin and manipulate this data and discredit it. I think if we hear that, we've got to say no, that is spin."
The figure was questioned by some health chiefs, with NHS England chief strategy officer, Chris Hopson, claiming not to "recognise" that estimate.
"We need to be very careful about jumping to conclusions about excess mortality numbers and their cause without a full and detailed look at the evidence which is now under way," he told BBC Radio 4's World at One programme.
Education minister, Robert Halfon, on Monday morning insisted that Rishi Sunak was treating the issue as a "top priority", but admitted that more needed to be done.
"The Government is putting (in) a lot of funding and doing everything possible.
"We know, of course, that many of these problems have been caused by the pandemic and the pressures on the NHS that we've seen over the past few years."
But Prof Banfield warned that patients will die due to the current state of the health service.
"The Government should deliver on its obligations to the public. It is just not true that the cost of resolving this mess cannot be afforded by this country.
"This is a political choice and patients are dying unnecessarily because of that choice."
Labour has blamed Government "mismanagement" for creating a sense of "jeopardy" around the health system.
Shadow health secretary Wes Streeting, who described staff shortages as the "heart of the crisis", said there was a "sense of jeopardy" regarding the health service.
He told BBC Radio 4's PM programme that the country was looking at the "consequences" of "more than 12 years of Conservative mismanagement" as he pointed to lengthy waiting lists and "enormous" staff shortages.
"It's also the situation we see now, which I think is unprecedented in the NHS, which is people no longer feel confident that emergency medicine will be there for them when they need it."
"Indeed, the NHS seems to be actively deterring people from going to accident and emergency departments unless it’s life threatening, because they are overwhelmed.
"And I think that's the sense of jeopardy, which is frightening so many people across the country."
While the Liberal Democrats called on the Government to recall Parliament.
Health spokesperson Daisy Cooper said: "NHS paramedics, nurses and doctors are this country's heroes but they have been left high and dry by the Government. They need help right now before more people die.
"I am calling for Parliament to return without delay. The Prime Minister must declare a major incident now to put the NHS back on a pandemic-style footing amid soaring numbers of deaths."
A Department of Health and Social Care spokesperson said that NHS staff do an "incredible" job.
"NHS staff do an incredible job and we recognise the pressures the NHS is facing following the impact of the pandemic," they said.
"That's why we've backed the NHS and social care with up to £14.1 billion additional funding over the next two years and this winter we have provided an extra £500 million to speed up hospital discharge and free up beds. We also awarded a 9.3% pay rise to the lowest earners in the NHS last year.
"The Health Secretary and ministers have met with unions several times and have been clear their door remains open to further discuss how we can work together to improve the working lives of NHS staff."
This article contains information from PA Media.