Committee Chairman Mike Rogers did not specifically identify the purported new threat nor its origin but referred several times to what he described as Iran's growing cyber espionage capabilities.

"I think they're (Iran) closer than we'd all like them to be to come in and cause trouble on our financial services networks," the Michigan Republican told a cybersecurity conference hosted by the U.S. Chamber of Commerce.

Classified briefings about the possible new keyboard-launched threats may have revived prospects for stalled measures aimed at boosting cybersecurity in the "lame duck" congressional session after the November 6 election, he said.

These secret briefings for lawmakers have highlighted a "threat that would target networks here from an unusual - careful here - source that has some very real consequences if we are not capable to deal with it," he said.

The concern was with nation states that are gaining a cyberwarfare capability beyond those that "we often talk about" Rogers said. An unclassified U.S. intelligence report last year said the governments of China and Russia were expected to remain "aggressive and capable" collectors of U.S. trade secrets, particularly in cyberspace.

Iran says it has been adding to its cyber clout since its disputed nuclear program was damaged in 2010 by malicious computer code known as Stuxnet, reliably reported to have been developed by the United States.

A U.S. financial services industry group last month warned banks, brokerages and insurers to be on heightened alert for cyber attacks after the websites of Bank of America and JPMorgan Chase experienced service disruptions.

Customers of Bank of America Corp (BAC.N), JPMorgan Chase & Co (JPM.N), Wells Fargo & Co (WFC.N), U.S. Bancorp (USB.N) and PNC Financial Services (PNC.N) have reported trouble accessing their websites, as unusually high traffic appeared to crash or slow down the systems in the past two weeks.

Rogers on Thursday reiterated his concerns about alleged Chinese cyber theft of U.S. trade secrets, describing Beijing as "ferocious about seeking information." He also cited what he called media reports that China likely was behind a disruption of a White House computer system disclosed this week.

"What people don't realize is that we are in war today in cyberspace," he said. "And this is the biggest national security threat I can think of that we are not prepared to handle in this country today."

A Senate bill backed by President Barack Obama that would have allowed for greater information-sharing between intelligence agencies and private companies has met opposition from both the U.S. Chamber of Commerce, which objected to additional regulation, and the American Civil Liberties Union, which is worried about privacy issues.

Rogers and Representative C.A. Ruppersberger, the top Democrat on the committee, have introduced separate bipartisan legislation that would clear the private sector to share information on cyber threats with the federal government and others on a voluntary basis.

(Reporting By Jim Wolf; Editing by Paul Simao)

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