Garda Headquarters has written to the Department of Justice, informing them that the force had lost more than one-third of their in-house permanent IT staff.

According to a confidential letter, seen by RTÉ's This Week radio programme, the force has been left heavily reliant, as a result, on the use of private sector workers to operate and maintain the State's most sensitive law enforcement and national security computer systems.

The document, which was sent in recent weeks, from the office of Acting Garda Commissioner Dónal Ó Cualáin to the Finance and Resources section of the Justice Department, says that 37% of the force's in-house IT specialists had been lost over recent years.

Garda HQ has prepared a business plan to counter the loss, which would see the number of in-house IT experts bolstered, the memo states.

The letter goes on to say that the situation has left the force with "a high degree of dependence on the main incumbent supplier of IT skilled resources, Accenture, to support our critical information systems".

Accenture is by far the largest single supplier of IT expertise to the force, with around €26m paid out per annum to the private firm, according to the most recent figures for 2016 which were seen by RTÉ. This compares with a total spend of approximately €50m across all private IT companies.

One Accenture contract with An Garda Síochána was the subject of a critical review by the Garda Internal Audit Unit (GIAU) last year.

The GIAU pointed out a series of concerns over how the contract was managed by the force, procurement issues, and a lack of a paper trail to explain how a new scheme of fees had been agreed to.

The letter goes on to say that the force would face "challenges" in attempting to transition to an alternative supplier if they wished to at some point in the future, given the "absence of sufficient numbers of permanent IT staff currently in position to manage such a transition".

One experienced IT expert, Colin Larkin, director of the consultancy firm MoQom, told RTÉ that the loss of such a high proportion of skilled computer experts posed a major challenge to any policing organisation.

He said that the current market for hiring IT specialists was "very competitive" with the gardaí having to compete with a major shortage of specialist IT workers globally and a high demand from private sector companies.

A spokesman for the Garda Press Office said they were not in a position to comment over the weekend on what is the status of their request for additional resources.