Another hospital has been placed in special measures after inspectors discovered it had been running for at least two months with potentially unsafe staffing levels.
The chief executive and chairman of The Queen Elizabeth Hospital, Kings Lynn NHS Foundation Trust have been replaced with a "hit squad" of high-performing health service officials tasked with urgently improving patient safety.
The foundation trust regulator Monitor took action after poor standards at the hospital were highlighted by the Care Quality Commission (CQC) following inspections earlier in the year.
The watchdog looked at staffing levels at the trust between 21 June and 13 August and found there had not been a single day on which the hospital had operated with the required number of staff.
The CQC also highlighted a lack of training in relation to dementia care and poorly performing risk management procedures, which it said was "putting patient care at risk".
It is the first NHS trust to be placed in special measures under a new crackdown on failing hospitals, other than the 11 hospitals with higher-than-normal death rates which entered following the Keogh review in July.
The new regulatory regime for hospitals takes inspiration from the Department for Education's "super-heads" programme. The trust will also be "buddied" with a high-performing partner, Guy's and St Thomas' NHS Foundation Trust, which will send senior staff to assist with reforms at the Queen Elizabeth.
Health Minister Lord Howe said that the Government was determined to create a "safer NHS" in which "substandard care will not be tolerated".
However, Labour accused the Government over cuts to nursing posts and said the dangerously low staffing levels seen at Kings Lynn were affecting other hospitals too.
"Hospitals across the country are in the same position," said the shadow health minister Jamie Reed. "David Cameron has placed hospitals on a financial knife-edge and another 450 nursing jobs were axed last month alone. Experts warned him of the central importance of nurse numbers in providing safe care, but he is forcing hospitals across England to operate without safe staffing levels."
The Royal College of Nursing has called for safe staffing levels and a number of reports, including Sir Bruce Keogh's review, also highlighted the problem. However, the Government has rejected calls to legislate on minimum staffing levels for wards.
The hospital was placed in the highest risk band by the CQC in a review of performance across all 161 NHS trusts published this week.
Professor Sir Mike Richards, chief inspector of hospitals said: "The failings we found at The Queen Elizabeth Hospital King's Lynn were unacceptable on more than one occasion.
"The concerns we found, coupled with information from our partner agencies and other regulators, were so great we felt it was necessary to request that Monitor intervene and place the trust in to special measures to assist in driving through improvements for patient care.
"CQC will continue to monitor this trust closely and our inspectors will be returning unannounced to check on whether improvements have been made and standards are being met."