Four people, including the former vice chairman and president of precision instrument maker Mitutoyo Corp., were served fresh arrest warrants Thursday for illegally exporting to Singapore measuring devices that can be converted for use in producing nuclear weapons.

Former Mitutoyo Vice Chairman Norio Takatsuji, 71, former President Kazusaku Tezuka, 67, and two others are suspected of exporting the products to the company's subsidiary in Singapore in July 2005 and understating the devices' efficiency data to dodge government curbs on sensitive exports.

The four have already been charged with exporting the products to Malaysia in 2001 in violation of the Foreign Exchange and Foreign Trade Law, and investigators believe Mitutoyo repeated such exports since around 1995.