Government Communications Headquarters (GCHQ) lost track of 35 laptops in 2008, including three classified as 'top secret', the Intelligence and Security Committee (ISC) has revealed.

GCHQ director Iain Lobban told the ISC, which was established in 1994 to examine the policy, administration and expenditure of GCHQ, that historically laptops were simply checked in and out and updated in the records.

The ISC criticised this "haphazard" approach to the allocation and location tracking of devices, and has demanded tighter security practices.

"The ISC considers that this formerly cavalier attitude towards valuable and sensitive assets was unacceptable. GCHQ must ensure that it controls, tracks and monitors its equipment effectively," it said.

Lobban claimed that the rapid deployment of personnel and assets to conflict areas had exacerbated the problem.

"A lot of the laptops are shipped out to sites in the theatres of war for communications means or to control equipment. Against an operational imperative, people perhaps took slightly hasty decisions without due process," he said.

However, Lobban admitted that its former control processes "were not sufficiently robust", and said that GCHQ had updated its procedures to check the location of every single laptop more regularly.

The news will make embarrassing reading for Downing Street, which recently gave the Information Commissioner's Office the ability to fine companies found guilty of breaching the Data Protection Act up to £500,000 from April 2010.