Patients arriving by ambulance at Oxford's casualty unit are to be left on canvas stretchers so paramedics can respond to other emergencies.

Ambulance staff outside the John Radcliffe Hospital

This expedient by Oxfordshire Ambulance Service follows concerns that its staff are spending between 40 and 60 hours a day looking after patients outside the accident and emergency unit at the John Radcliffe Hospital, in Headington, because the hospital is delaying admissions.

From December 9, senior officers will order ambulance crews to leave after 15 minutes.

Unison, the health union, is worried the situation will put lives at risk and threaten paramedics' careers, because they could be blamed if patients die after being left at the hospital.

The union claims the JR uses ambulances as holding tanks, to prevent it missing the Government target that patients must be treated within four hours of admission.

One paramedic, who asked not to be named, said: "For the past six months or more we have been piled up outside casualty and there's usually about five or six of us waiting. One of my colleagues has waited there for eight hours.

"Casualty staff won't put patients on trolleys and let us go. They've even dismantled the trolleys."

In a joint response, the Oxford Radcliffe Hospitals NHS Trust and Oxfordshire Ambulance Trust declined to say anything about the trolleys.

The ambulance trust's chief executive, John Nichols, also refused to comment directly on the service's new policy.

The statement said the A&E unit had moved into partly-completed facilities this week while a £12m unit is built.

It said the smaller temporary home had "brought into sharp focus the fact that it is now physically impossible to accommodate ambulance and paramedic crews waiting with patients in the department".

But critics said the problem had been obvious for several months.

The statement also said: "In extreme circumstances, when the whole hospital is so full that immediate access to A&E is impossible, then the two organisations have agreed a set of protocols to ensure the smooth handover of patients.

"Both organisations are conscious they need to ensure the smooth handover of patients.

"Both organisations are conscious they need to provide the proper capacity and resources so their nurses, doctors and paramedics can maintain their professional duty of care to their patients effectively."

Philip Bolley, Unison convenor for Oxfordshire Ambulance Trust, said a rough survey showed paramedics spent about 40 to 60 hours a day outside the JR.

He added casualty staff would not place new patients on hospital trolleys, because once admitted they had to be treated within the four-hour deadline.

Mr Bolley said: "I started complaining about this in September because it was becoming unacceptable and the hours were increasing, including some patients who needed close observation.

"But if we consciously know a patient needs to be closely monitored, then we wouldn't want to leave them, and I'm pushing for an agreement so if we feel a patient needs observing we'll stay with them."