Japan’s fair trade watchdog has searched the offices of Bridgestone and 10 other tyre makers as part of a probe into rigged military supply contracts, according to a BBC report.

The investigation reportedly centres on alleged collusion aimed at pushing up the price of tyres supplied to the Japanese army and air force.

Bridgestone said it would not comment as the inquiry was still under way, the BBC said.

Japan’s Defence Agency orders about 2 billion yen ($US18 million) of tyres every year, according to local media reports cited by the BBC.

A spokesman for the Japanese Fair Trade Commission reportedly said it had also raided the offices of Yokohama Rubber Co. and Toyo Tyre & Rubber Co.

The BBC noted that Japanese military supply contracts have previously come under scrutiny, notably in a 1999 investigation into the alleged price-fixing of fuel for military aircraft.