Britain's government wants to quickly deploy full body scanners at U.K. airports to fight an expanded terrorist threat, but privacy concerns _ and fears that children may be exploited _ seem likely to slow the plan.
Privacy campaigners and children's rights groups say the technology, now being tested at Manchester Airport, violates British and European law by producing sexually explicit images of children.
They say the machines cannot be allowed because they can clearly show a child's genitalia when a boy or girl walks through the airport scanners, which are designed to reveal concealed liquids, explosives or weapons to assure the safety of commercial air travelers.
Ian Dowty, legal adviser to Action on Rights for Children, said he believes it would be a criminal offense to operate the scanners or to direct anyone to operate them if they are used to produce images of children under the age of 18.
"If anything produces an indecent image of anyone under 18, that is unlawful and is in fact a criminal offense," he said. "As we've seen on the Internet, these machines clearly show genitalia, that in our view must result in an indecent image by any definition."
He said any new security apparatus must comply with British law as set by Parliament and that it is up to the legislature to consider whether to change the law to allow the new generation of full body scanners to operate.
Prime Minister Gordon Brown has called for greatly expanded use of the machines in response to the thwarted Christmas Day attack on a plane preparing to land in Detroit after flying from Amsterdam. Officials believe the suspected bomber's explosives _ sewn into his underwear _ would have been picked up by the person operating the scanner.
Home Secretary Alan Johnson said Monday afternoon that the first scanners should be set up at London's Heathrow Airport within three weeks. He said more sniffer dogs would be deployed and more passenger profiling would be considered.
Johnson also said all U.K. airports would be required to have trace equipment capable of detecting explosives in the air by the end of this year _ but cautioned that no single technology would be 100 percent successful against terrorists.
Britain's Transportation Department has promised to develop a "code of practice" governing body scanner use that would address privacy concerns.
Terry Whittock, vice president of scanner-maker Rapiscan Ltd., said it is very likely the machine would have detected the explosives being carried on board.
"We can't say for certain that it would have stopped this threat, because we don't have access to all the information, but there is a very high expectation that it would have," he said. "That is exactly what it was designed to deter."
Others, including a British lawmaker, have said the machine would not have been useful in spotting the explosives intended for use over Detroit.
"The machines amount to little more than gimmickry, and the government is going to face a huge legal obstacle," said Simon Davies, director of Privacy International. "It can't identify a substance, it can only identify an abnormality, and the rest of it is human judgment."
Davies said a letter from privacy groups convinced Manchester Airport officials not to use the scanner on children. He said that even if Brown persuades Parliament to modify British law to make the scanners acceptable that they would still be in violation of the European Convention on Human Rights, which would take precedence in this case.
The privacy issue also is dampening enthusiasm for the technology on mainland Europe, although officials at Amsterdam's Schipol Airport plan a major expansion for use to screen U.S.-bound flights.
The scanners in use there differ from the ones being tested in Britain, and officials say they are being fitted with software that addresses privacy concerns by projecting a stylized human figure onto the computer screen rather than using the actual body image of the person being scanned.
In Germany, officials said the scanners would only be considered once privacy concerns are resolved.
Dietmar Mueller, spokesman for the German Data Protection Commissioner Peter Schaar, said the commission believes the machines infringe the privacy of both adults and children.
"At the moment, we're not aware of a machine that would sufficiently secure privacy rights," he said, also raising concern about the effectiveness of the scanners.
In France, lawmakers discussed the scanners in 2008, but the idea of deploying them was dropped after privacy concerns were raised.
Associated Press Writers Juergen Baetz in Berlin and Arthur Max in Amsterdam contributed to this report