Travellers passing through airports in Los Angeles and New York will be subjected to a controversial “virtual strip search” by computer from this week.

The new method of searching for concealed weapons is made possible by a machine that uses “millimetre-wave” technology to produce a computerised image of travellers’ naked bodies.

Although the computer strip searches are voluntary and travellers can still request a pat-down instead, critics say it is a matter of time before they replace metal detectors.

Barry Steinhardt, the director of the American Civil Liberties Union’s programme on technology and liberty, said: “The images are quite revealing. I guarantee you, you’ll be seeing [them] on the internet.”

Los Angeles airport and John F. Kennedy airport in New York received their first body scanners this week, each of them at a single checkpoint. Another machine has been on trial since October at Phoenix Sky-Harbour airport in Arizona.

In Britain, giant versions of millimetre-wave scanners have been used at seaports to look through lorries in search of illegal immigrants.

The images are black and white and bear little resemblance to a photograph. Nevertheless, they clearly display the most intimate curves of the human form.

The body scanners, which cost as much as $150,000 each, are in limited use at international airports in seven countries and at a handful of courthouses and jails in five states.

Another 30 body scanners are expected to be installed at other US airports this year.

Travellers polled yesterday by the Los Angeles Times were unimpressed. “Honestly, it’s embarrassing and extremely violating,” said Grace Kim, 28.

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