Nurses from hospital trusts in Suffolk and north Essex are set to strike next month as part of an ongoing pay dispute with the government.
The Royal College of Nursing (RCN) has confirmed workers at East Suffolk and North Essex NHS Foundation Trust, which runs Ipswich and Colchester hospitals, and West Suffolk Hospital will walk out on January 18 and 19.
RCN members at Norfolk and Suffolk NHS Foundation Trust and the NHS Suffolk and North East Essex Integrated Care Board will also take part in the strike action.
Two days of nurses' strikes were held in England, Wales and Northern Ireland on December 15 and 20, which resulted in more than 40,000 patient appointments and procedures being rescheduled.
But nurses in Suffolk did not take part in those walkouts as not enough workers voted in favour to trigger industrial action.
West Suffolk Hospital, in Bury St Edmunds, declared a 'critical internal incident' earlier this week due to significant A&E pressure.
The East of England Ambulance Service also declared a critical incident status earlier this week amid a high volume of 999 calls and hospital handover delays.
It comes as the public were warned that the health service remains under extreme pressure in the lead-up to Christmas.
The move to strike comes amid a dispute over pay after government officials declined a formal offer of negotiations rather than industrial action.
Pat Cullen, head of the RCN, said the union had been left "with no choice" but to arrange January strikes.
She said: "The government had the opportunity to end this dispute before Christmas but instead they have chosen to push nursing staff out into the cold again in January.
"The public support has been heart-warming and I am more convinced than ever that this is the right thing to do for patients and the future of the NHS."
Health Secretary Steve Barclay said: "While union members will not be going ahead with strikes over Christmas, we are disappointed they have announced further co-ordinated strikes in January to cause maximum disruption at a time when the NHS is already under extreme pressure.
"The unaffordable pay demands of unions would mean taking money away from frontline services and cause further delays to care."
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