FIVE of Scotland's health boards are seeing delays of at least three times the target A&E waiting times of four hours - and one health board recorded a wait of over 24 hours.

A snapshot survey by the Sunday Herald revealed the lengthy waits experienced by patients in some A&E departments last weekend.

The target is that patients should be seen, treated, and discharged or admitted to a ward within four hours of arriving in A&E. But in five out of 14 health boards, the longest waits were at least 12 hours.

NHS Greater Glasgow and Clyde said the longest wait between December 22 and January 6 was 25 hours.

Meanwhile, NHS Lanarkshire recorded a wait of 20 hours and 45 minutes at Wishaw General ­Hospital, and 17 hours 14 minutes at Hairmyres Hospital last weekend.

The maximum wait in hospitals in NHS Ayrshire and Arran was just over 14.5 hours, while in NHS ­Grampian it was 12 hours 48 minutes at Dr Gray's Hospital in Elgin.

NHS Forth Valley and NHS ­Highland also experienced lengthy delays, with waits of just over 12 hours and seven hours respectively.

High demand at hospitals across Scotland has led to operations being cancelled due to a shortage of beds.

Emergency departments across the UK have been struggling, with some in England declaring major incidents and calling in extra staff.

David Chung, vice-chair of the Scottish Board of the College of Emergency Medicine and an A&E consultant in Ayrshire, said ­pressure on casualty departments was "not sustainable".

He said the issue was not a sudden rise in attendances at A&E, but that a system designed to be more "efficient" was now under pressure due to factors such as an increase in elderly patients. He said: "Scotland has got around 6000 less hospital beds than it did in 2005. Having a reduced number of beds has made it very difficult to cope with what in some ways was a predictable problem."

Chung also warned A&E departments were in a position where having to deal with critical incidents - such as a major car crash or flu outbreak - would be "challenging".

"Unfortunately, now it has reached the point where we have become so efficient we don't have the reserves we need to have to deal with ­something unusual," he said. "We are running at 95 to 100% ­capacity and that leaves you with no extra 5% to deal with critical incidents."

He added: "A&E can cope with large numbers of people with ­injuries and things which are ­short-lived, but what they can't cope with is the whole system becoming gummed up.

"The four-hour target was chosen because if you are falling behind on that, it is an indicator that there is a problem in the system which may be affecting patient safety … If people are waiting 12 hours for a bed, that is an indicator there is something very seriously wrong with the system.

"Unfortunately, mistakes are going to be made and people aren't going to get the care they deserve because, with the best will in the world, in a high-pressure situation people are going to miss things."

Theresa Fyffe, director of the Royal College of Nursing (RCN) Scotland, said the situation was a symptom of wider problems in the NHS, which include patients stuck in hospital beds because there is no care package for them at home, and too few staff for growing demands.

"Health boards have to do the best they can in the short-term, but we really need an urgent long-term wholesale review of health and social care if we are to avoid repeated crisis in our NHS in the future," she said.

"With the NHS on red alert just now it is unlikely to cope well if there was a sudden drop in temperatures or a significant outbreak of flu. It would potentially have huge ramifications for patient care, with even more pressure on waiting times, more and more operations being delayed and people simply not receiving the care they deserve and need."

NHS Forth Valley said its figures had still to be verified, but one patient waited just over 12 hours last weekend out of around 400. A spokeswoman said: "Although some patients did wait more than four hours, the majority were seen well within the four hour target."

Liz Moore of NHS Ayrshire and Arran said the longest wait was just over 14.5 hours and apologised for the delays.

At NHS Lanarkshire, Heather Knox said it were not alone in seeing high levels of activity. She added: "Our staff work hard to avoid delays and we regret any occasion where this occurs."

NHS Fife's Scott McLean said it was understood some patients waited more than four hours last weekend, but figures were not verified.

Three health boards - NHS Lothian, NHS Borders and NHS Dumfries and Galloway - failed to provide any figures.

Scottish Government figures show 88.8% of patients were seen within four hours in Scotland's A&E departments over Christmas and New Year.

A Government spokesman said an additional £10 million was made available to boards to assist with winter pressures this year. He said local plans are in place across Scotland.

"Boards are working hard to deliver these plans and ensure long waits in A&E are minimised," he said. "The four-hour target is rightly ­challenging, and we will go on protecting NHS investment and improving systems to enhance performance."

He added that long-term plans are in place, including integration of health and social care to cut the number of people waiting in hospital for home care to be arranged.

"This will mean fewer people unnecessarily delayed in hospital, freeing up beds and easing the pressure on A&E."