The Irish Nurses and Midwives Organisation has said there were 569 patients on trolleys in hospital emergency departments this morning - the highest number ever recorded.
The worst affected hospitals were Cork University Hospital with 48 patients waiting; Beaumont Hospital had 45 patients on trolleys and the Mid West Regional Hospital in Limerick had 44 patients waiting.
Today's morning figure broke yesterday's record of 511 patients on trolleys.
Later, the number of patients on trolleys had fallen to 259.
The HSE said that many planned operations are being postponed due to overcrowding.
While the HSE is currently unable to give a figure on the number of procedures affected nationally, it said some planned operations were being deferred at University College Hospital Galway, Cavan General, Our Lady of Lourdes in Drogheda and the Mid West Regional Hospital in Limerick.
Some routine surgery has also been deferred at Cork University Hospital and at Beaumont Hospital in Dublin.
There are around 11,000 inpatient beds in hospitals but over 1,500 are not available for new admissions for a variety of reasons.
These include cost savings, refurbishment, infection control and the fact that over 500 beds are being occupied by patients who are ready to be discharged but who can not go home or have no nursing home place.
It says that much of the increased pressure in emergency departments is due to people suffering with swine flu and other seasonal illnesses common at this time of year.
A peak is also common due to the post holiday period and the recent cold snap has also resulted in pressure on the system.
Fine Gael's Health Spokesperson Dr James Reilly described today's figures as shocking and said Government policy on health was hitting frontline services.
Dr Reilly said there were fewer beds available to patients, longer waiting times and more cancelled operations, which was exacerbating the problem in emergency departments.
Shortage of non-consultant doctors
A consultant in emergency medicine at Cork University Hospital has said a shortage of non-consultant hospital doctors was contributing to delays in treating people who attend emergency departments.
Chris Luke said many junior doctors were leaving Ireland when qualified and were being replaced by non-Irish doctors or locums.
Speaking on RTÉ Radio, Dr Luke described the staffing of frontline hospital services as precarious.
Meanwhile, Labour Health Spokesperson Jan O'Sullivan has called for a 'new approach to tackling the crisis in our healthcare services'.
She added: 'Letting people languish on trolleys in corridors and examination rooms, for hours on end or even longer, is completely unacceptable in this day and age.'
All planned operations at Cork University Hospital are to be postponed tomorrow.
Its Clinical Director, Professor Richard Greene, said the cancellations were due to the pressure on the hospital's emergency department.
Prof Greene said the number of patients on trolleys was the worst he had seen in his two years as clinical director.
He said he hoped the situation would improve at the hospital next week, when the medical admissions unit opens.