Patients attending accident and emergency wards are being abandoned on trolleys in other parts of hospitals without nursing supervision because there is nowhere else to put them, according to nurses and doctors .

Patients who arrive at hospital needing emergency treatment are increasingly having to spend the night in units designed for people undergoing heart surgery or having broken limbs plastered because A&E units are under such pressure and have too few beds to cope with the growing influx of people needing care.

The disclosures, from the Royal College of Nursing (RCN) – which is holding its annual meeting in Liverpool this week – as well as the body representing A&E doctors, dramatically highlight the NHS's struggle to cope with increasing numbers of emergency patients caused by a combination of winter pressures, the ageing population and cuts to social care support.

They call into question the ability of hospitals to provide safe care in the wake of the Mid Staffordshire hospital scandal and the health service's obligation to make £20bn of efficiency savings by 2015. The Department of Health acknowledged the unprecedented pressures on emergency departments and said they were currently reviewing hospital hours and community-based care to tackle the problem.

Karen Webb, east of England regional director of the RCN, which represents most NHS nurses, said that patients were being "scattered round hospitals like confetti" because A&E staff have nowhere else to put them. Growing numbers are being left on trolleys in corridors, the union claims. It is concerned that the health of patients left in such places may suffer because nurses only check on them occasionally and their treatment may be delayed.

Some A&E patients are staying overnight in catheter labs after patients with heart trouble who undergo procedures there during the day have gone because some hospitals are having to resort to "desperate measures", said Webb.

"That [use of catheter labs] has involved upwards of 20 patients at a time in places in the east of England and is becoming a fairly regular occurrence."

Webb described how A&E patients are dispersed around so many different wards of hospitals at nighttime in a bid to find them a bed, and records of their moves not inputted because no relevant staff are on duty then, that doctors the next day have to form what they call "safari teams" to go around looking for them. Patricia Marquis, the RCN's director for the south-east of England, said hospitals across the region were treating patients in corridors, with some now formalising the practice by putting up screens around them to protect their privacy and designating certain nurses as "queue nurses" to check on those who are being held, for treatment or admission once a bed becomes free in places other than the A&E unit.

Day surgery units, where patients have a new hip or knee fitted during the day, are also being used as other overnight overspill areas, said the College of Emergency Medicine, which represents casualty doctors. It claims hospitals are having to resort to unusual ways of trying to cope with the sheer number of A&E patients who need to be admitted.

Dr Clifford Mann, the college's registrar and an A&E consultant in Somerset, said: "The pressures on emergency departments in the UK are unprecedented at the moment. They have been building steadily in the last few years but have come to a tipping point in the last six months to the point where the number of incidents of concern have started to significantly take off."

There have been examples of patients who need to be resuscitated because they have collapsed at A&E before they have been seen yet being resuscitated while still on their ambulance trolley, Mann said.

"Things that are meant to never happen are now starting to happen and things that should happen infrequently are now becoming commonplace because of the sheer pressure on A&E services."

A&E services across the UK are hamstrung by "significant understaffing" -- too few A&E consultants, other doctors and also experienced nurses, Mann said. Many hospitals which need at least ten consultants to offer high-quality A&E care 24 hours a day all year round have only seven, he said.

Labour last week highlighted official A&E figures showing that hospitals across England failed to meet the key target of treating 95% of patients within four hours for the previous two months. The A&E at the Norfolk and Norwich hospital in Norwich came under such pressure last month that it and the local ambulance service set up a tent outside in which to treat people.

The Department of Health acknowledged that A&E units are under increasing pressures. "We know there are increasing pressures on A&E departments – they are seeing an extra one million more patients compared to two years ago but despite this are still trying to ensure patients don't face excessive waits for treatment", said a spokesman.

He added: "At a local level, the NHS needs to ensure it has proper plans in place to deal with high demand on A&E. But it's obvious that this isn't just about A&E services in isolation it's also about how the NHS works as a whole, and how it works with other areas such as social care.

"Local GPs are already leading great work in different parts of the country to prevent patients having to go to A&E in the first place, while Sir Bruce Keogh is already leading reviews of the way the NHS can work seven days a week, and of the structure of emergency care."