Some 6,000 Psychiatric Nurses were to begin an overtime ban from 31 January as part of an escalating campaign of industrial action over pay

It comes as hospital A&E departments are expected to be dangerously overcrowded today in the wake of yesterday's national walk-out by more than 35,000 nurses in pursuit of higher pay..

Some 6,000 psychiatric nurses are to begin an overtime ban today as part of an escalating campaign of industrial action over pay.

The psychiatric nurses are refusing to work overtime today, tomorrow and on the 5, 6 and 7 February.

They said they will then escalate their industrial action to full strikes on 12, 13, and 14 February.

Meanwhile, another 50,000 patients and vulnerable people are at risk of having hospital care and services cancelled next week as striking nurses threaten to ramp up their dispute.

Members of the Irish Nurses and Midwives Organisation (INMO) are now vowing to go ahead with two more 24-hour strikes next week on Tuesday and Thursday if no meaningful offer is made to resolve the crisis.

Buoyed up by loud public support, the placard-waving and chanting nurses angrily pounded the pavement in the winter chill and marched on the picket line from 8am yesterday.

But hospitals were left to cope with just an emergency service - forcing the cancellation of surgery, outpatient clinics and community services for 25,000 people.

Although hospital A&Es were struggling to maintain a service with reduced staffing, thousands of patients stayed away or attended busy GP surgeries.

However, trolleys were filling up again yesterday evening as many seriously ill patients, whose condition may have been exacerbated by the freezing temperatures, had to seek emergency treatment.

Liam Woods, head of acute services in the HSE, said meetings with unions today would prepare for the next round of cancellations of patient appointments next week.

He warned the "cumulative effect" of cancellations will make it more difficult to reschedule appointments, causing serious delays.

There is no immediate sign of an intervention by the State's industrial relations troubleshooting bodies to halt next week's industrial action.

The Workplace Relations Commission and Labour Court are on standby but will not get involved until they feel there is some softening of positions.

That either means the nurses park their demand for an upfront pay rise, or the Government finds a way of giving it to them.

The Government may be open to considering the possibility of a review of nurses' roles and responsibilities.

But the big obstacle is the INMO's demand for a wage hike before the current deal runs out in 2020.

The Government fears a deluge of knock-on claims from other public servants if it gives them a pay rise.

Nurses will come under intense financial pressure as they prepare to take to the picket lines again after already losing a day's pay. Health Minister Simon Harris signalled they could also be hit in the pocket by a wage freeze and stalled pay rises for breaching the public sector pay deal.

He said the Department of Public Expenditure and Reform would consider imposing legal sanctions for breaching the agreement in the coming days and weeks, but did not specify when.

"I don't think the Government should be in that space today," he said yesterday. "The Government isn't in that space today. The Department of Public Expenditure and Reform will legally consider that in the coming days and weeks but the priority for Government is to try and engage within the confines of the Public Service Stability Agreement."

He insisted the public sector pay agreement was clear that there could not be claims that increased costs. Mr Harris said the nurses' demand for a 12pc pay rise was valued at €300m and was a claim that would increase costs and trigger knock-on claims.