More than 1,000 health workers in Northern Ireland are not being paid the National Living Wage, the Department of Health has admitted.
A total of 1,316 permanent and temporary members of staff are still awaiting an increase to their pay, which was due to be implemented two months ago.
The National Living Wage was increased from £7.20 to £7.50 in April, for those aged 25 and over.
The increase means a £500 a year pay rise to full-time workers who do a 38-hour week.
However, the Department of Health (DOH) said 1,316 members of staff within the region's five health trusts, the Ambulance Service and Blood Transfusion Service, have not had their pay uplifted in line with the National Living Wage hourly rate.
SDLP MLA Patsy McGlone said those affected include domestic support workers, housekeeping assistants, drivers and nursery assistants. "This is clearly unacceptable. It is certainly less than the same staff would be earning in England, Scotland or Wales," he said.
The department, which has come under criticism for failing to comply with the statutory requirement, has insisted staff will receive the pay increase, plus arrears, in July. Workers aged under 25 are not included.
The DoH said that in the absence of a Health Minister "the department cannot go further than compliance with the statutory requirement under National Living Wage legislation, and thus staff under 25 will continue to receive a base salary of £14,437".
The spokesman added: "It will be for a new Health Minister, when appointed, to consider the NHS Pay Review Body recommendation that pay point 1 is adjusted so that all workers receive the National Living Wage."