"This matter requires more attention," Jeremie Waterman, head of the U.S. Chamber of Commerce's China division, told a U.S. government panel hosted by the U.S. Trade Representative's office.

It "has risen substantially in importance over the last year, year and a half," Waterman said at an annual hearing on China's compliance with World Trade Organization rules.

In one recent case, two Chinese citizens in Kansas City, Missouri, were charged with attempting to pay $100,000 for stolen trade secrets from Pittsburgh Corning Corp, an affiliate of PPG Industries Inc (>> PPG Industries, Inc.) and Corning Inc (>> Corning Incorporated), at its Sedalia, Mo. facility. The Justice Department said the pair were trying to purchase the trade secrets so a rival plant could be opened in China.

U.S. chemicals giant Dupont (>> E I Du Pont De Nemours And Co) also is in the midst of a legal battle over allegations that China-based Pangang Group Steel Vanadium & Titanium Co Ltd (>> Pangang Group Steel Vanadium & Titanium) conspired to steal its trade secrets.

Earlier this year, The New York Times reported that an Austrian-based employee of the Massachusetts wind-energy company American Superconductor (>> American Superconductor Corporation) stole intellectual property from the firm and sold it to Chinese wind turbine manufacturer Sinovel (>> Sinovel Wind Group Company Limited) for $1.5 million.

Peter Dent, a vice president at Electron Energy Corp, told the government panel that both large and small U.S. companies face "persistent and increasingly complex cyber-attacks (from China) in an effort to steal intellectual property from company computer networks."

Defending trade secrets against the attacks was "very difficult" and a costly drain on resources, he said.

Companies need the U.S. government to take action, which could include suspending "trade benefits to countries sponsoring these actions," Dent said.

The DuPont, Pittsburgh Corning and American Superconductor cases are "just the tip of the iceberg," a U.S. industry official said. U.S. companies are dealing with rampant "state-supported theft of trade secrets," he said.

The hearing on Wednesday was part of USTR's annual evaluation of how well China is meeting the commitments it made to join the World Trade Organization in 2001. A report is usually released on December 11, the anniversary of Beijing's accession to the WTO.

U.S. exports to China have soared since China joined the WTO in 2001 and the country is now the third-largest foreign market for U.S. goods. But business groups told the USTR-led panel China maintains a extensive web of discriminatory policies that prevent U.S. companies from making additional sales and investments in the world's second-largest economy.

Both the U.S. Chamber of Commerce and the U.S.-China Business Council called on Wednesday for a "bilateral investment treaty" that would open up areas of the Chinese economy to investments by U.S. companies.

China maintains foreign ownership restrictions in nearly 100 business sectors, the business groups said.

Industry officials also complained about continuing Chinese piracy and counterfeiting of U.S. goods, and urged the U.S. government to aggressively challenge Chinese government subsidies that undermine U.S. competitiveness.

(Reporting by Doug Palmer; Editing by David Brunnstrom and Stacey Joyce)

By Doug Palmer