Britain sought to reassure air passengers over privacy concerns on Tuesday after full body scanners were introduced at two major airports in the wake of the Detroit bombing scare.
Transport Secretary Andrew Adonis said images taken by the scanners -- introduced at London's Heathrow and Manchester airport on Monday -- were deleted immediately after passengers were cleared by security.
He said only a small proportion of passengers will be asked to go through the full body scanners -- which produce detailed images of the person's body shape -- but anyone who refuses will not be able to board their flight.
"At the moment, people accept that they are subject to a pat-down search when they have gone through the metal detector," he told BBC television, adding that such a search was "a pretty intrusive procedure".
"A body scanner is in the same category -- it is very important to stress that the images which are captured by body scanners are immediately deleted after the passenger has gone through the body scanner," he added.
The United States has accelerated the installation of body scanners at airports since the attempted Christmas Day attack on a jet bound for Detroit from Amsterdam.
Britain is among several European countries, including The Netherlands, installing the scanners after Nigerian Umar Farouk Abdulmutallab was charged with trying to down the passenger plane.
In a written parliamentary statement Monday, Adonis confirmed that anyone who refused to undergo a full body scan would not be allowed to travel.
"In the immediate future, only a small proportion of airline passengers will be selected for scanning. If a passenger is selected for scanning and declines, they will not be permitted to fly," he said.
