A union has said some staff at a hospital trust have been paid thousands of pounds less than they should have following a pay agreement.

Unison represents healthcare support workers at Colchester and Ipswich Hospitals, run by the East Suffolk and North Essex NHS Foundation Trust.

The union and trust had agreed to introduce a new, national pay-band structure for healthcare assistants, but the union said some had still not received their full wage.

The trust’s chief executive Nick Hulme said some staff were receiving more than £4,000 in back pay and talks were ongoing with the union.

Unison said workers had been paid “for years on the lower band 2 of the NHS Agenda for Care salary scale” – but had been performing duties that would place them on a higher band.

The duties included blood monitoring, inserting cannulas and doing echocardiograms, which are scans used to look at the heart and nearby blood vessels.

The union claimed some of the longest-serving staff received thousands of pounds less than they were promised following the recent pay agreement.

It also said some weekend and night staff had received nothing to date.

Staff had planned to take strike action in the summer before the agreement was reached.

Unison eastern regional officer Lucas Bertholdi-Saad said the healthcare support workers were “essential to the running of the NHS”, but the trust had used them “to provide care on the cheap”.

“The workers were delighted when the trust finally agreed to give them the respect, recognition and pay they deserved earlier this year,” he said.

“But they had a nightmare before Christmas when they discovered the money in their wage packets was thousands of pounds less than had been promised.

“East Suffolk and North Essex must do the right thing and give staff their due.”

Mr Hulme added: “We have worked in partnership with Unison and all our staff representatives for the past three years to introduce this new, national pay band structure for healthcare assistants.

“We have jointly agreed our approach with Unison and signed a memorandum of understanding. Some colleagues are receiving more than £4,000 in back pay.

“We will continue to work with Unison and talks are ongoing.”