Up to 10 ambulances were queuing at the Royal Gwent Hospital

It follows a day when all hospitals in Wales, except Wrexham Maelor, were under serious pressure.

Up to 10 ambulances queued up outside the Royal Gwent in Newport, while Nevill Hall in Abergavenny, was shut to all but critically-ill patients.

The Welsh Ambulance Trust said Monday's problems eased in the south-east, with no crews tied up waiting with patients.

The Royal College of Nursing has called for action to avoid a repeat of Monday's problems, and wants the Assembly Government to set up walk-in clinics.

Ambulance managers said lives had been at risk. They said they had not been able to answer other emergency calls because crews had been forced to wait in queues to hand over patients.

Dr Gibbons said he was concerned that "exceptional emergency pressures" had continued to cause problems.

He said he had asked officials to stay in close contact with health trusts to help them manage the situation.

Red alert status

The minister now plans to visit A&E departments across south Wales to see for himself the pressures that staff were facing and to discuss how the situation could be improved.

As well as more beds, nurses leaders want the assembly government to follow England's example by bringing in nurse-led walk-in clinics.

Richard Jones, of the Royal College of Nursing, said he had seen such clinics work well in Bristol.

"Really it's like a walk-in treatment centre where the nurse is there and the nurse actually follows out correct protocol to treat minor illnesses and ailments of patients.

"When I was in Bristol, they gave me the statistics of last month and 800 patients were referred from the A&E department to the walk-in centre."

On Monday night, regional ambulance officer George Murphy said that all the acute hospitals in the south east region had been on red alert status.

He said there had been delays the University Hospital of Wales in Cardiff, as well as at Prince Charles Hospital in Merthyr Tydfil.

But, he added, the worst hit was the Royal Gwent Hospital in Newport.

'Remaining busy'

The Royal Gwent Hospital said it had tried to free beds by moving existing patients who were well enough to other hospitals including nearby St Woolos Hospital.

A spokesman for the NHS trust said non-critical patients had also been diverted to Caerphilly District Miners' Hospital.

By Tuesday, the situation across Wales had eased considerably. spokesman for Cardiff and Vale NHS Trust said: "We remain busy but we don't have any ambulances waiting outside casualty."

Bro Morgannwg NHS Trust said staff were coping under pressure in the A&E department at the Princess of Wales Hospital, Bridgend, and the local accident centre at Neath Port Talbot.

Some planned operations had to be cancelled because of a shortage of beds for emergency patients.

"At both sites we are managing to get patients into the departments from the ambulances but we are under significant pressure," a spokeswoman said.

"We will do all we can to get beds but will have to wait for discharge later in the day or patients will be put in beds that were to be occupied by elective admissions," she added.

"It is likely that we will be cancelling a number of operations today and tomorrow. "

Concerns were raised last month about emergency patients being forced to wait for hours on trolleys at the University Hospital of Wales in Cardiff.

An e-mail from a senior nurse to politicians wrote of patients being treated like "vegetables".