The US Justice Department is investigating possible violations of antitrust law in the optical disc drive industry. Optical disc drives read or write data on media such as CDs, DVDs and Blu-ray discs.

Sony Corp said that its US optical disc drive operations were under investigation for possible violations of antitrust regulations. Hitachi and Toshiba are also being investigated and have acknowledged receiving subpoenas.

Sony Optiarc America, which supplies a lineup of optical disc drives, has received a Justice Department subpoena. Company spokesman Chisato Kitsukawa said the company is “fully cooperating with US authorities” and did not comment other details about the case.

Japan's Hitachi Ltd and Toshiba Corp also said that their optical disc drive operations with South Korean partners were being investigated. Hitachi said its joint venture with LG Electronics, Hitachi-LG Data Storage, had received a Justice Department subpoena and that the unit was also under investigation by European Union and Singapore regulators.