Ministers say the technology will boost security, speed up pre-boarding checks, and could end the restrictions on travelling with liquids and laptops. The equipment, similar to CT scanners used in hospitals, is already being installed at London's Heathrow Airport. It provides a clearer picture of a bag's contents, which staff can zoom in to and rotate for inspection.

Currently, passengers taking liquid in their cabin baggage are restricted to containers holding no more than 100ml, which must be shown to security staff in a single, transparent, resealable plastic bag of about 20cm (8in) x 20cm.

The limits have been in place since November 2006. Their introduction ended a ban on liquids in the cabin imposed three months earlier, when British police said they had foiled a plot to blow up as many as 10 planes using explosives hidden in drinks bottles. Announcing the new plans, Prime Minister Boris Johnson said the scanners would cut down on "hassle" for travellers and improve security.