Sodexo has come under fire from trade unions over staff payment issues at its £75m full services contract with Brighton & Sussex University Hospitals NHS Trust.
Non-medical staff, including caterers, porters and cleaners, have not been paid properly since Sodexo took over the contract on 1 December, said the GMB union.
Staff should be paid weekly but some have been missing extra hours and basic pay.
Mark Turner, from the GMB, told the BBC: "Payments used to be made fortnightly, the company wanted to pay them weekly and were confident they could do that. These are low paid workers who have their bills like the rest of us."
A spokesperson from Sodexo said the issues with enhanced and overtime payments had resulted from system and data errors during a complex mobilisation.
"Contracted employees have now received correct payments for their normal hours since the start of our services.
"For those employees affected by the system errors, we immediately set up payroll clinics where we have made payments via either cash or bank transfer. We apologise for any inconvenience caused."
The hospital said it was "monitoring the situation" closely and was in regular contact with Sodexo.
By Janie Manzoori-Stamford
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