Hospital doctors may be responsible for up to 400 patients a night and junior doctors may often be the most senior person on duty, according to a report from the Royal College of Physicians.

Each doctor cares for an average of 61 patients each night but it ranges from one to 400, research from 670 medical teams in England and Wales showed.

In comparison, a doctor cares for just 11 patients on average during the day.

The data also revealed that junior doctors with less than two years’ experience on NHS wards can often be the most senior person on duty at night.

Dr Andrew Goddard, director of the medical workforce unit at the Royal College of Physicians, which carried out the survey, described the results as “worrying”.

He said: “The very low number of doctors per patient at night in some hospitals raises serious concerns for patient safety and there are also worrying reports of very junior doctors being left unsupported, which urgently require further investigation.”

An anonymous survey was sent to all consultants in England and Wales asking them to record the make-up of their team and how many patients were being cared for.

The study, to be published in the journal Clinical Medicine, was carried out to assess the impact of the European Working Time Directive (EWTD), which limits the number of hours a trainee doctor can work to 48 per week.

It found day cover on wards ranged from two to 65 patients per junior doctor, with the highest ratio per doctor in Wales and the lowest in London, where there is a higher number of trainees.

John Black, president of the Royal College of Surgeons, said: “This new evidence from the RCP corroborates what surgical trainees have been telling us for months.

“Under EWTD, rotas are unworkable to the point of being dangerous and junior doctors without adequate supervision are being asked to make critical decisions beyond their competence.”