Four years after the 7 July 2005 terrorist attacks on the London Tube, a review of the government’s counter-terrorism policy says the rail service remains “extremely vulnerable” to similar attacks, reports.

The review, compiled by the Commons Home Affairs Select Committee, stated that the Tube will always be a “high-profile and iconic target” for terrorists.

The report also adds that the rail service could never adopt an airport-style security system because of the huge volume of daily passenger traffic.

The review has revealed these findings even as a number of counter-terrorism exercises have been staged post the 2005 attacks to better prepare staff. Since then, a new system, Airwave, has also been introduced for underground communications between the emergency services and London Underground staff.