Hospital chiefs have warned that patients' lives are at risk due "dangerous" bed shortages the NHS faces this winter.
Hospital trust representatives say an emergency bailout is needed to pay for extra beds and staff as attempts to improve the healthcare service's finances this year have failed.
They fear that lives could be lost as patients have to spend increasingly long periods of time waiting to be seen across Accident and Emergency (A&E) wards, according to a new report by NHS Providers, which represents trusts across England.
The organisation's chief executive Chris Hopson told The Observer that hospitals are "dangerously short" of beds and that they may not be able to cope this winter, expected to be the worst in over a decade.
NHS Providers called on the government to make between £200m and £350m available immediately after a £1bn government initiative to free up 2,000-3,000 hospital beds by September has failed.
The existing target to see the majority of A&E patients within four hours has not been met for two years now, according to the report.
The goal for this summer was set at 95%, but NHS figures revealed that just over 90% of patients were treated within four hours in recent months.
Hopson said: "Last winter the health service came under pressure as never before. This winter could be worse."
"Hospitals this winter will still be too full of people whom we can't discharge, even though they are medically fit to leave, because of problems with social care. Failure to do so leaves us dangerously short of capacity."
He added that little progress has been made in the past year to free up more beds and cut waiting times.
"That means that it could be even worse than last year, when there were far too many patients waiting more than 12 hours on a trolley or in the back of an ambulance to be seen,"Hopson said. "Unless we get extra money, patients will be put at greater risk as local trusts won't have the beds and staff they need to meet the extra demand we will face."
The call for money comes ahead of a meeting between NHS leaders and Prime Minister Theresa May which is taking place next week.
The Downing Street called a meeting with NHS bosses and the regulator to check on plans for this winter.