The U.S. Justice Department is investigating possible violations of antitrust law in the optical disc drive industry, a spokeswoman said on Tuesday.

Spokeswoman Gina Talamona declined to discuss what companies were involved or give details about the probe but Sony, Hitachi and Toshiba have all acknowledged receiving subpoenas about the case.

Optical disc drives read or write data on media such as CDs, DVDs and Blu-ray discs.

Sony Corp said on Monday that its U.S. optical disc drive operations were under investigation for possible violations of antitrust regulations, and indicated that other regulators could follow suit.

Sony Optiarc America, which supplies a lineup of optical disc drives, including those for DVDs, CD-ROMs, CD-Rs and Blu-ray discs, received a Justice Department subpoena, a Sony spokesman said.

Japan's Hitachi Ltd and Toshiba Corp said on Tuesday that their optical disc drive operations with South Korean partners were being investigated internationally for possible antitrust violations.

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.

Toshiba said its joint venture with Samsung Electronics, Toshiba Samsung Storage Technology Corp, had also received a subpoena and that it was answering queries from authorities in other regions.

Since Christine Varney took over as the head of the department's antitrust division this spring, the unit has begun a series of probes.

They include an investigation into allegations that International Business Machines abused its dominance of the mainframe business to squeeze rivals.

There is also an investigation into possible anti-competitive practices involving credit derivatives.

The department is also investigating telecoms companies for potential antitrust violations. Smaller telcos have complained that the giants -- AT&T and Verizon Communications

-- used their market share to squeeze out smaller rivals.

Smaller firms have also protested against the exclusive deals that cellphone companies made with handset makers.

The Justice Department was also critical of a deal hammered out by Google and the Authors Guild to allow Google to put millions of books online. The division urged a judge assessing the class action settlement to reject it.

(Reporting by Diane Bartz; Editing by Derek Caney)

Japan Antitrust law Electronics