Anti-paedophile groups in the UK are forcing Manchester Airport has been forced to rethink trials of its invasive new X-ray machine.

The high tech scanners allow the use of a full-body scanner, which can instantly detect any hidden weapons or explosives without passengers having to remove any of their clothing such as shoes and belts. The technology removes the need to frisk passengers and is expected to speed up the security process at airports. However it means that passengers are stark naked in front of security staff.

But British children's advocate Action on Rights for Children (ARCH) said the technology would fall foul of the country's Protection of Children Act, which states it is an offence to "'show" and "make" an indecent image of a child. It did not matter that the image was only on the screen for a few moments there as the law has a clause that outlaws "pseudo-photographs".

If the gear is allowed a paedophile could defend themselves in court saying that they were only looking at images for a short time and weren't storing them. Manchester Airport initially argued that its scanner was lawful and exempt from the child pornography laws because it was used for the "prevention and detection of crime". But now it admits that the machine might be illegal.