Oct. 21 (Bloomberg) -- AT&T Inc. sued Samsung Electronics Co., LG Display Co., AU Optronics Corp. and other manufacturers of liquid-crystal displays over claims they colluded to fix prices of panels sold in the U.S.

AT&T, the biggest U.S. phone carrier, filed the complaint yesterday in federal court in San Francisco. The lawsuit claims Samsung, the world’s biggest maker of liquid-crystal displays, and more than six other display makers “formed an international cartel illegally to restrict competition in the United States in the market for LCD panels.”

“The conspiracy included communications and meetings in which defendants agreed to eliminate competition and fix the prices of LCD panels that were ultimately incorporated into LCD products that they knew would be sold in California and the United States,” according to the complaint.

In March, Hitachi Displays Ltd., a unit of Japan’s Hitachi Ltd. which isn’t named in AT&T’s suit, became the fourth company to plead guilty in a global U.S. display panel price- fixing investigation.

LG Display, the world’s second-largest liquid-crystal- display maker, Chunghwa Picture Tubes and Sharp Corp., all three of which were named in the AT&T case, agreed to plead guilty in November to the U.S. claims and pay $585 million in criminal fines. AT&T’s case relies on the Justice Department’s investigation.

Shares Fall

Samsung shares fell 2.3 percent to close at 735,000 won in Seoul, while LG Display dropped 0.5 percent to 32,750 won. AU Optronics declined 2 percent to NT$32.05 in Taipei trading.

Samsung spokeswoman Lee Soo Jeong wasn’t immediately available for comment. Spokesmen for Hsinchu, Taiwan-based AU Optronics, Seoul-based LG Display and Tokyo-based Sharp said they hadn’t received details of the case and couldn’t comment.

“The material impact on the panel stocks may be limited, since the lawsuit can drag on for several years,” said Bevan Yeh, who helps manage about $1.2 billion at Prudential Financial Securities Investment Trust Enterprise in Taipei. “It’s inevitable that there will be some knee-jerk reaction.”

AT&T, based in Dallas, argues its AT&T Mobility unit purchased more than 300 million mobile wireless handsets for resale to its customers. The prices of those handsets were artificially inflated because of the price-fixing, the carrier said.

The case is AT&T v. AU Optronics, 09-04997, U.S. District Court, Northern District of California (San Francisco).

To contact the reporter on this story: Joel Rosenblatt in San Francisco at jrosenblatt@bloomberg.net; Chinmei Sung in Taipei at csung4@bloomberg.net.

Last Updated: October 21, 2009 04:09 EDT