A new body-scanning security system is being used in Amsterdam's Schiphol airport to search for metals and explosives hidden under passenger clothing. The 'security scan' system uses "millimetre wave technology" to display head-to-toe images of people.

It takes about three seconds to go through the scanner. Passengers step into the open device and assume the "ballerina position" - standing with both arms up in the air - according to airport officials .

Security officers view the digital images in a separate room so that other passengers can't see them. And the person's face is blocked out on the screen to further ensure privacy.

There have been some concerns from passengers regarding the safety of the radio waves, Reuters reports .

Schiphol airport is Europe's fourth-busiest airport hub, often handling up to 160,000 passengers a day. The body scanners are currently an optional alternative to waiting in long security queues for metal detectors, or being frisked by security officials.

Birmingham Airport launched a new security system based on biometric technology back in February this year. Dubbed Project Iris, the system uses iris-scanning technology to identify travellers and speed up immigration checks. Iris was first introduced at Heathrow Airport in March 2006.