The UK Security Service - MI5 - is the latest public sector body to suffer technology problems.

A report from the intelligence and security committee, published on Thursday, warned that a planned upgrade of the Service's computer systems is continuing to go awry.

The Service, more commonly known as MI5, has seen costs soar while capabilities have been cut.

The scale of the budget overruns, however, has been kept out of the public domain on grounds of national security.

The report said: "The Service is part-way through the project to renew its IT infrastructure, which is now estimated to cost £***."

"This project has given rise to a number of problems over the past couple of years and the management team within the Security Service has been changed.

"We have been told that the project will now deliver less capability than previously planned and it will cost at least 50 per cent more than originally estimated, but it will be operational earlier than originally projected."

The committee expressed concern that MI5 lacks sufficient project managers or expertise to manage all their IT and capital projects at the same time.

"We have raised these concerns with the director general, who has assured us she is conscious of the problems and is taking steps to address them. We will continue to monitor this."