The HSE has said it needs Garda clearance before it can publish a report into allegations of child abuse in a foster home.
A copy of the report, which has been under wraps since 2012, was sought by the Joint Oireachtas Committee on Heath and Children.
However, HSE officials insist they are constrained by an ongoing Garda probe into the claims that a young person with intellectual disabilites was abused over a prolonged period.
Health service bosses have also defended spending over €124,000 on the unpublished report.
A consultancy firm commissioned to do the report, Conal Devine and Associates, was not appointed through a tendering process.
It charged a daily rate of €1,145 to investigate the claims.
In a letter to the Dail's Public Accounts Committee (PAC), the HSE said it had not been required to make the 2010 appointment under normal tendering rules due to the exceptional circumstances involved in the case.
It said Mr Devine was identified as an individual who had previously dealt with sensitive health service investigations involving young and vulnerable people.
"The matters required to be dealt with urgently involving a team with professional experience and expertise in the conduct of inquiries, including collaboration with an Garda Siochána and other statutory authorities, as well as a knowledge of social work and disability services," the HSE said in the letter.
It said Mr Devine had charged fees for 84 days' work as well as mileage and other expenses.
But the HSE said he had actually worked for 170 days on the report, which was submitted in March 2012.
Mr Devine also did additional follow-up work at no extra cost, the HSE said.
In the letter to the PAC, the HSE said it needed clearance from the Garda and the Office of the Wards of Court before the report could be published.
As well as the Garda inquiry, the case is also the subject of civil proceedings.