The NHS provider sector has generated a year-to-date deficit of £886 million, with the sector forecasting a year-end deficit of £873m, show figures published by NHS Improvement.
According to the regulator, NHS providers are "experiencing one of the most challenging winters on record" due to a huge increase in the demand for urgent and emergency care.
It's analysis shows that 5.34 million patients attended providers' A&E units between October and December 2016, which is 200,000 more than at the same period last year, and a 3.5 percent increase in the number of patients requiring major further in-hospital treatment.
"This intense demand for emergency treatment coupled with a significant reduction in bed availability has led to providers collectively underperforming against several key national healthcare standards, and having to postpone some planned care," it notes.
On the financial side, the sector ended the quarter £886 million in deficit, but NHS Improvement stressed that this financial position is £1.3 billion better than at the same point last year and that fewer providers ended the period in the red (135 providers versus 91 last year).
Measures to curb "excessive agency staff spending" are continuing to have a positive impact, it insists, highlighting that two-thirds of providers reported reduced agency costs with the sector delivering a £505 million improvement over the last nine months.
Nevertheless, 66 percent of acute trusts are forecasting a year-end deficit, as well as 60 percent of ambulance trusts, 30 percent of mental health trusts, 29 percent of specialist trusts and 17 percent of community trusts.
NHS Confederation chief executive Niall Dickson said the figures were a "tragedy".
"The NHS had made huge strides to treat and care for patients promptly but the latest figures show a further deterioration – and behind those figures lie real suffering for patients and exhausted staff.
"The danger now is that efforts to transform services that government has rightly been championing are derailed because of all the effort that has to go into keeping the service going and trying to balance the books."
He added that additional funding for social care is an 'immediate priority', as the system is currently "letting down" more than one million elderly people who are not receiving the support they need.
Also commenting on the figures, Labour Shadow health secretary Jonathan Ashworth MP said the "sustained underfunding of the NHS is stretching the finances of NHS hospitals beyond their limits" and stressed that "it will take a heroic effort by NHS staff to meet even the predicted year-end target in the face of chronic neglect by the Government".
"The money which had been set aside for NHS transformation funding, which should be improving services and bringing the deficit down in future, has instead had to be used to manage this year's figures," he argued, adding that "cuts to social care have driven up hospital attendances while the Government's inept workforce planning has forced hospitals to drain resources on expensive agency staff".
"The Government urgently need to provide a long-term, sustainable financial package to guarantee the NHS services which patients need for the future."