Regulators in the US, South Korea and Japan have served Samsung Electronics with subpoenas as part of an investigation into possible anti-competitive practices in the flat-panel display market.

Samsung becomes the second LCD (liquid crystal display) manufacturer to announce that it's been contacted in connection with the investigation, the existence of which was not known until LG Philips said yesterday that it had been visited by regulators in the same three countries.

Both LG Philips and Samsung pledged to cooperate with the investigation.

"Samsung Electronics is strongly committed to fair competition and ethical practices and forbids anti-competitive behaviour," said Cho Sung In, a spokeswoman for the company in Seoul.

Among other LCD manufacturers, Taiwan's AU Optronics said it had not been contacted by regulators and Sony said its joint-venture with Samsung, S-LCD, had not been contacted. Officials at Sharp could not immediately confirm whether the company had or had not been subpoenaed.

The investigation comes on the heels of probes into the DRAM (dynamic RAM) and SRAM (static RAM) markets.

The DRAM investigation has snared many of the largest players in the multi-billion dollar computer memory-chip industry.

Market leaders Samsung and Hynix pled guilty in 2005 to price-fixing and received fines of $300m and $185m respectively. Japan's Elpida Memory had to pay a $84m fine and Germany's Infineon Technologies AG was sentenced to pay a $160m fine.

In October several manufacturers of SRAM chips said they had been subpoenaed by the US DoJ (Department of Justice) although they did not disclose the nature of the DOJ's requests. The companies were Cypress Semiconductor and the US units of Mitsubishi Electric, Samsung Electronics, Sony and Toshiba.