The Northern Ireland Office (NIO) spent almost £3.4 million last year on consultants and substitute staff, it was revealed today.

Planning for large projects like the redevelopment of Magilligan Prison, Co Londonderry, were included in the bill.

Assembly Public Accounts Committee (PAC) member John Dallat claimed costs were being inflated.

"It is initially suggested that consultants' fees will be a particular price, but then of course the cost of the projects increase and the consequent fees become a gravy train for those involved in the more expensive projects and the taxpayer is billed for the lot," he said.

"It raises serious questions because consultants are not accountable to the electorate and that needs to be monitored.

"It could be described as a money-making machine or as an opportunity to create a money-making machine."

Cash is generally spent on consultants for surveying, architects' work, legal business and management.

The NIO is responsible for the Prison Service, forensic science, Youth Justice Agency, Compensation Agency and the Public Prosecution Service.

A total of £718,690 was devoted to the Prison Service. That was linked to matters like planned redevelopment of Magilligan, Co Londonderry, changes to healthcare provision and other specialist services like aptitude tests for recruitment competitions.

A Prison Service spokesman said of the bill: "The Prison Service only engages consultants where it does not possess the required level of in-house expertise.

"The main areas of expenditure relate to the ongoing estate management developments and the options appraisal study which was undertaken in relation to the replacement prison for Magilligan.

"Other areas related to Investors In People and Healthcare Assessment Reviews and an aptitude test for recruitment campaigns."

Mr Dallat added: "The more we employ consultants the less expertise is left within the civil service to do the job.

"There's a danger that we become not only dependant on consultants but they take over decision-making."

The near £2 million consultancy total for the NIO was disclosed in its annual report for last year. It rose from £1.9 million the previous year. Almost £1.4 million was spent on substitute staffing.

The report said: "The department has adopted a policy of only engaging consultancy support where the particular skills or resources required to deliver the service are not available in-house."

Earlier this year the PAC criticised use of consultants within the 11 Executive departments.

One consultancy source claimed: "The big consultancy under-estimate is the legal bit.

"Civil servants' contracts need to be changed when you transfer assets (like the creation of Northern Ireland Water)."