One of the London's busiest A&E departments has been ordered to make improvements after regulators found that there were not enough doctors to meet demand.
North Middlesex University Hospital's urgent and emergency care services have been rated "inadequate" by Care Quality Commission (CQC) inspectors.
Staff at the hospital told inspectors they were worried about patient safety because of the competency of middle grade doctors. These doctors were often left in charge of the emergency department overnight - with no consultant presence in the department after 11pm, inspectors were told.
In some cases, emergency patients were forced to wait until morning to find out whether they were to be admitted or sent home because doctors were "unable or unwilling to take decisions", the report says.
"Members of staff told us there was a culture of not calling consultants out at night. They said that middle grade doctors seemed to assume that it was acceptable to leave patients in ED (emergency department) overnight, thus treating it as if it were a hospital ward," the report adds.
Meanwhile nurses told inspectors they spent a "substantial amount of time supporting and advising more junior doctors".
In recent weeks it has emerged that the General Medical Council has issued preliminary warnings to North Middlesex Hospital leaders because of a lack of training for junior doctors. The doctors' regulator threatened "withdrawal of approval for the trainees in the emergency department".
Sir Mike Richards, CQC chief inspector of hospitals, said: "People going to the emergency department at the North Middlesex University Hospital NHS Trust are entitled to a service that provides safe, effective, compassionate and high quality care. When we inspected we found that patients were waiting for a long time to be seen, without being assessed by a doctor in the first place.
"North Middlesex University Hospital is one of the busiest A&E departments in London - so it is worrying that we found that there were not enough experienced doctors on call to deal with demand. We have strongly encouraged the trust to engage with other organisations across the local health and social care system to resolve this challenging issue.
"We have already seen some progress since that original inspection. A new leadership team is in place in the emergency department, there are moves to appoint more senior doctors - and I note that the trust is calling on consultants from other departments within the hospital to provide the routine daily support to A&E which is so badly needed.
"The evidence from our latest inspection last week is that North Middlesex's emergency department has turned a corner, but there is still much more that needs to be done. We will be watching their progress very closely."
North Middlesex University Hospital medical director Dr Cathy Cale said: "We are extremely sorry for the current problems in A&E and for the long waiting times for some patients.
"We are committed to getting back to the standards that we and our patients expect and, working with our health partners, are taking all the necessary steps to address the concerns raised, particularly the shortage of doctors which lies at the heart of it."
In a joint statement, Niall Dickson, chief executive of the General Medical Council, and Professor Ian Cumming, chief executive of Health Education England, said: "Significant concerns have been raised about the care provided in the emergency department at North Middlesex University Hospital Trust and about the lack of proper support for and supervision of doctors in training.
"We are pleased to see that a number of key improvements have already been made and a programme of further measures is being put in place over the next few weeks.
"This includes the recruitment of a new clinical director, additional medical staff and other changes to relieve the pressure on the department and support doctors in training. There is more to be done to make sure that the improvements can be sustained and that the department can cope in the long term with the extra pressures it faces.
"In the meantime the GMC and HEE - the two organisations responsible for postgraduate medical training - have placed conditions on the continuation of medical training posts in the emergency department and the situation will be closely monitored with daily rigorous checks.
"We have made it clear that we will not hesitate to act if we consider patients or staff are being put in unsafe situations."