The leader of Britain's biggest union has attacked government targets on A&E waiting times, which he claims have led to queues of ambulances outside hospitals.

Unison general secretary Dave Prentis said on Monday that paramedics are being held back from attending emergency calls because they are often delayed by a backlog caused by central targets.

With ministers insisting that patients are seen, treated and discharged from A&E within four hours of arrival, Prentis claimed NHS staff are being forced to hold cases outside the hospital doors in order to help meet the target.

"It's happening for two reasons - one, the A&E unit is overcrowded, cannot take more people in," he told the Tonight With Trevor McDonald programme.

"It's also happening, we believe, because of targets, and the fact that one of the targets is that you only have a four hour wait in A&E otherwise the hospital is penalised.

"This means that the A&E unit and the management want to make sure that those A&E units are not overcrowded. So patients wait in ambulances until it is clear for them to go into the A&E unit.

"And you've got to remember the ticking time of the wait in the hospital does not start until the person is registered within the hospital. So the four hour target that they've got to meet only applies when the patient has been transferred from the ambulance into the hospital and been registered."

Context

However NHS emergency access chief Sir George Alberti said a few rare examples had been taken out of context by the programme, which showed pictures of queues of ambulances outside East Surrey Hospital.

"It is wrong to suggest that A&E departments are not meeting the A&E targets," Sir George said.

"We know that 19 out of 20 patients are seen, treated and discharged within four hours - some in an even shorter time. Because of this the majority of A&E departments do not experience ambulance queues.

"A few individual examples of hospitals does not make this the norm. We make no apology that through this four hour target A&E departments offer patients faster access and a significant improvement in the care they receive.

"Since October 2000 there have been clear rules that all patients should be registered within a maximum of 15 minutes of arrival at A&E irrespective of whether they are still being cared for in an ambulance outside of the A&E department."