Mounting pressures on hospitals mean that patients are being treated in storerooms, frail and elderly patients are being moved around in the middle of the night and ambulances are queuing outside A&Es, leading nurses have warned.

Major incidents in hospitals are usually seen only in the busy winter months but are now becoming a problem all year round, the Royal College of Nursing (RCN) said.

The college, which is holding its annual congress in Glasgow, said that across England, the hospital sector is feeling the strain of financial pressures and increased demand.

It highlighted a series of issues facing local hospitals that are “adding to the chaos” at hospitals across England. These include:

• Beds being placed in corridors and patients treated in storerooms in order to move people out of A&E.

• Ambulances queuing outside A&E units or the regular use of “jumbulances” – large ambulances which can accommodate multiple patients – to treat patients while they wait to enter the units.

• Patients, often frail older people, being moved at night due to intense pressure for beds.

• Hospitals running with no spare capacity at all.

Janet Davies, the RCN’s chief executive and general secretary, said: “Having once been the preserve of the worst weeks of winter, overwhelming pressure and major incidents have sadly become the new normal in our hospitals. Units are having to be closed and operations cancelled due to the level of demand when there is no extreme weather, and no major outbreaks of infectious diseases.

“Despite the best efforts and dedication of the staff, these pressures are affecting patients at every stage in their treatment.

She said the pressures were leading to patients getting sicker and needing to stay in hospital for longer as a result. “It is time we had a serious look at how long hospitals can continue to function when they are consistently underfunded and understaffed.”

Janet Davies, the general secretary of the Royal College of Nursing. Photograph: Martin Godwin/The Guardian

Janet Youd, an A&E nurse in Yorkshire and chair of the RCN emergency care association, said she could not guarantee patients would get safe care in an emergency department.

She said: “I have been an emergency care nurse for 25 years, and the news is that the attrition rate of emergency nurses leaving emergency departments is at a level it has never ever been before.

“Many emergency departments are struggling but managing to fill their shifts with expensive agency shifts, but they are not necessarily emergency nurses.

“That means that if you or I have an emergency today ... you could go to an emergency department and it would be sheer luck that you had an emergency nurse there with the right skills and the right training to treat you.”

The British Medical Association has separately called for an end to the ongoing process of hospital bed closures. The doctors’ union overwhelmingly passed a motion at its annual conference on Monday which said “trends in reducing hospital beds have gone too far and need to be urgently re-evaluated”.

Dr Mary McCarthy, a GP, told the BMA’s annual conference: “Hospital beds in the UK have been steadily eroded without the corresponding increase in social care that is needed to support this move. The UK has less than 300 beds per 100,000 population and in Shropshire, where I am, it’s less than 200.

“In the Irish Republic it’s about 500, in Belgium it’s over 650, in France it’s over 700, in Germany it’s over 800, in Austria it’s over 700, in Romania it’s over 600. Do we really need to keep cutting beds? Are we not finding that our hospitals are bulging at the seams with people who should be there but are discharged home too early and unsafely?”

Figures collated by the King’s Fund show the number of hospital beds in both acute and mental health facilities has halved to about 150,000 in England over the last 30 years.