EU lawmakers have delayed the introduction at airports of full body scanners, machines that generate images of passengers - minus their clothes.
MEPs voted for a further study on the implications for privacy and health.
Computer pictures generated by the scanners give an outline of passengers' bodies beneath their clothes.
Supporters say they detect hidden objects not picked up by traditional metal detectors. But critics say they amount to a virtual strip search.
The new scanners have already been introduced in several US airports and have been tested around the world.
The European Commission - which supports their implementation - has given assurances that the scanners will not be used routinely on all passengers.
And it would be a faster and less intrusive alternative to frisking or strip-searching people.
Where scanners are in use, security staff can pick out individuals to stand in a booth while three pictures are taken of the person in slightly different positions.
Within seconds, a scanner produces an image of the body.
What shows up is the naked human form and anything that may be concealed, such as a gun or drugs.
"The Commission believes that body scanning methods can complement in a very effective and efficient way the existing security measures at airports," said spokesman Jens Mester at EU headquarters in Brussels, Belgium.
But others are unconvinced.
"It is unacceptable, if scanners are used, these are machines that see you completely naked," said Martin Schulz, leader of the socialist grouping in the EU assembly.
"This is an offence against human dignity," he added