Cleaners, porters, catering and other hospital workers are to strike over plans to move their jobs out of the NHS.
Hundreds of staff from East Suffolk and North Essex Foundation Trust (ESNEFT) will walk out between 19 and 23 August at Colchester Hospital and community sites, including Felixstowe and Aldeburgh hospitals in Suffolk.
Public service union Unison said members were concerned outsourcing contracts would threaten pay and conditions, and put patient safety at risk.
ESNEFT said it was still in discussion with Unison and its members.
Unison said staff at Ipswich Hospital received fewer days of annual leave, less sick pay and had missed out on a one-off payment for NHS staff when their jobs were outsourced.
Unison’s regional organiser Sam Older said: “The trust told staff they were being sold out of the NHS months ago but they are still waiting to be told why.
“These workers are proud to work for the NHS and support patients. They don’t want to strike but feel they’ve been left with no choice.”
He called the trust’s outsourcing plan “nonsensical”.
Sarah Gray, a facilities team leader in Aldeburgh, said: “Our pay grade and what we do every day should be no different from other health workers at the hospital.”
ESNEFT chief executive Nick Hulme said: “Our top priority is patient care and safety and we will be working hard to plan for the period of industrial action to make sure everyone who uses our hospitals continues to receive the service they expect.
“We are disappointed to learn that Unison has gone down this route while we are still actively involved in ongoing conversations with them and their members.”
He said the trust was listening to staff and a full business case had not yet been submitted to the board.