MPs have criticised managers in charge of moving the GCHQ spy centre operations for not taking into account the cost of moving its IT infrastructure, which consequently cost £308m.

GCHQ decided to relocate in 1997, but managers "lost track of the scope and cost of the technical transition" by concentrating too much on its new building, the Public Accounts Committee concluded.

"This case was obviously bound to involve a major technological move, [and] GCHQ continued to perceive it as a building project for far too long," the report stated.

The Committee noted that the GCHQ management board only began to realise its omission when carrying out Year 2000 compliance work.

By that time the estimated cost of the move had risen to £450m, with the transition spread over two years.

Treasury officials were unwilling to fund the spiralling costs, instead forcing spy chiefs to accept a revised transfer budget of £308m, a 700 per cent increase on initial estimates.

In an effort to cut costs, parts of the IT systems will be kept running at the old Oakley buildings until 2012, adding £43m to the cost.