Body scanners being tested at Germany’s Hamburg airport have had a thumbs down from the police, who say they trigger an alarm unnecessarily in seven out of 10 cases, according to a newspaper.

The weekly Welt am Sonntag, quoting a police report, said 35 per cent of the 730,000 passengers checked by the scanners set off the alarm more than once despite being innocent.

The report said the machines were confused by several layers of clothing, boots, zip fasteners and even pleats, while in 10 per cent of cases the passenger’s posture set them off.

The police called for the scanners to be made less sensitive to movements and certain types of clothing and the software to be improved. They also said the US manufacturer L3 Communications should make them work faster.

In the wake of the 10-month trial which began on September 27 last year, German federal police see no interest in carrying out any more tests with the scanners until new more effective models become available, Welt am Sonntag said.

The European Parliament backed on July 6 the deployment of body scanners at airports, but on condition that travellers have the right to refuse to walk through the controversial machines.

Worried about embarrassing intrusion into people’s privacy, the parliament said the scanners should only produce images of “stick figures” and that any data must be immediately destroyed.

Concerned about the potential health risks, lawmakers also called for a ban on the use of X-ray scanners that use ionising radiation.

The use of scanners caused an uproar in the US last year because they produce a graphic image of a person’s body, giving rise to the name “naked scanner”.