More than 1,000 NHS workers have started voting on whether to take industrial action in a row over jobs and staffing.
Members of Unite at Barts Health NHS Trust in London are being balloted over the next few weeks on whether to launch a campaign of industrial action.
Last year, a campaign by Unite activists and union reps - which included strike action - paved the way for the workers to be transferred to NHS employment.
The cleaners, caterers, porters, security guards, ward hosts and domestic staff had previously been employed by Serco.
Unite said the workers were part of a group of staff who were transferred onto NHS employment from a private contractor, but have not received a lump sum the union says they are entitled to.
Unite general secretary Sharon Graham said: "Over 1,000 workers who won their rights to be NHS workers are now fighting against low pay and understaffing at Barts. They’re employed by the NHS now so they should be paid the lump sum like everybody else.
"The workers have a proud history of fighting for fairness and winning. Unite will not accept the lowest paid workers at the Trust being short changed."
A Barts Health NHS Trust spokeswoman said: “A number of our staff were still employed by Serco on 31 March 2023 and do not qualify for the lump sum under the terms of the national NHS pay deal, but we are working with them to see if industrial action can be avoided.”
