Home Secretary David Blunkett unveiled plans to recruit 1,000 extra spies into MI5 last week – a move that will see the home security service expand by 50%.

The announcement comes in response to the perceived threat of terrorism to the UK, and will focus on the surveillance of suspects and the protection of high profile targets. Most of the new staff will work for MI5’s A4 division, which specialises in following and watching suspected terrorists 24 hours a day.

MI5 also wants to recruit more Arabic, Kurdish and Persian speakers to infiltrate Islamic groups thought to be involved with Al-Qaeda.

It is thought MI5’s budget accounted for £200m of the £1bn spent on the UK’s three intelligence agencies last year.

Although MI5 has contracts with at least two agencies – Bartlett Scott Edgar and Tribal GWT – it has not disclosed what role these agencies will have in the new recruitment drive.