The Western Trust has been asked to explain why there was an underspend of £8million on adult learning disability services.
Local families, politicians and campaign groups have expressed outrage at the underspend, which they claim has had a major impact on the delivery of respite care and adult disability services.
The Trust has confirmed an £8million underspend across Derry, Tyrone and Fermanagh over the last number of years.
The underspend was discovered after a review was carried out in 2013 by the Regulatory and Quality Improvement Authority.
Critics claim that as a result, hundreds of families have been left with no respite care, and less staff have been available to provide care and support to patients and their families.
A spokesperson says the Trust is investing an additional investment of £2.3 million in the service this year, as well as working with other agencies to address the problem.
Omagh and Fermanagh Councillor Stephen McCann says he is seriously disturbed by this revelation, he wants the Western Trust to explain how this happened.
MLA's are expected to meet with the Western Trust on Friday to discuss the issue.