Jeans giant Levi Strauss & Co is testing radio-frequency identification technology (RFID) hang tags on clothing shipped to two retail outlets in Mexico and one in the United States.

But the move is being criticised by consumer advocates as an invasion of privacy rights and because Levi Strauss has violated their call for a freeze on item-level RFID.

Levi's, however, says the unnamed retailers have asked it to trial RFID to track inventory at the unnamed test stores, and that it has no plans to use RFID in any of its 18 Levi's brand stores.

The item-level hang tags are identified as having an RFID chip in them, and are removed when the garment is purchased.

"It's absolutely not embedded," said Jeff Beckman, director of worldwide and US communications for Levi Strauss in San Francisco. "It's readable from 1 to 3 feet and really has no value to anyone," other than for inventory tracking.

RFID uses microchips to track items via radio waves that can be detected at a distance. But privacy advocates fear that embedded tags will enable people's movements to be tracked without their knowledge or consent.

Privacy and civil liberties organisations in 2003 called for a moratorium on RFID-chipped items for consumers until more technology-specific information is available.