The body scanners can see through clothes, and thus see any suspicious materials on the body of the passenger, such as the explosive material used by the Nigerian terrorist.

The body scanners are controversial, because they can see through clothes, which is an invasion of privacy for the passenger. Apparently, however, it is possible to let software do the checking, and only when there is something suspicious, the alarm will go off so that a manual search can take place.

The machines will be in place in about three weeks. They will be used on all passengers travelling to the US.

Until they are in place, all passengers will be thoroughly searched. As the Nigerian terrorist hid the explosives in his underwear, the body searches may include passengers' private parts, says Mr Erik Akerboom, the Dutch national coordinator for counterterrorism.