Investigative authorities have questioned Takashi Usami, former chairman of Mitsubishi Fuso Truck & Bus Corp., over an alleged false report issued in connection with a fatal accident caused by a defective vehicle in 2002, informed sources said Sunday.

Usami, 63, resigned as chairman of the firm in mid-April to take the blame for the company's long delay in recalling Mitsubishi Fuso large trucks and buses featuring defective wheel hubs.

Investigators grilled Usami as part of efforts to establish a case against him and other executives suspected of issuing a false report on the fatal accident in violation of the road traffic law, the sources said.