Prosecutors searched the offices of several electrical machinery makers Thursday over allegations that the companies rigged bids for projects at Narita airport.

The companies involved include Mitsubishi Electric Corp., Fuji Electric Systems Co. and Toshiba Corp.

Narita airport, the main international gateway to Tokyo, was operated by the state-run Tokyo International Airport Authority since it opened in 1978 until it was privatized last April. The authority was in charge of the project when the alleged bid-rigging occurred.