TOKYO (REUTERS) - Japan's All Nippon Airways, which operates the world's biggest fleet of Boeing Dreamliners, said it found damage to the battery wiring on two 787 locator beacons during checks after the devices were identified as the likely cause of a fire on another aircraft in London this month.

The damage was slight, but the beacons have been sent to the manufacturer, Honeywell International, for inspection and the airline has informed local aviation regulators, an ANA spokesman, Ryousei Nomura, said.

British investigators probing the fire aboard an Ethiopian Airlines Dreamliner at Heathrow airport are focusing a possible pinched wire on an emergency beacon and on condensation in the plane, which has higher humidity levels than other aircraft.

ANA has taken the built-in locator beacons out of its eight domestically operated Dreamliners with the permission of local regulators and has inspected and put back those on its 12 787s that fly international routes.

The beacons are designed to guide rescuers to downed aircraft, although in most cases close radar tracking and eyewitness reports allow air traffic controllers to pinpoint crash sites.