Pentagon chief Leon Panetta.

Washington -

The Pentagon announced on Thursday that it is taking new steps to try to clamp down on leaks of classified information, saying unauthorised disclosures undermine national security and in some cases rise to the level of criminal acts.

Pentagon press secretary George Little said in a statement that Defence Secretary Leon Panetta has ordered him to join the Pentagon's top intelligence official in monitoring all “major, national level” news media reports for unauthorised disclosures of secrets.

Panetta also reiterated guidance issued by his predecessor, Robert Gates, that the Pentagon's public affairs office should be the only source of Defence information provided to the news media in Washington.

Little announced these steps after Panetta testified in closed session before the House Armed Services Committee on the matter of recent leaks of classified intelligence information. Joining Panetta at the hearing was the Joint Chiefs chairman, Gen Martin Dempsey, and the Pentagon's top lawyer, Jeh Johnson.

“The unauthorised disclosure of classified information jeopardises national security and is a violation of department regulation, policy, and, in certain cases, a criminal act that should be prosecuted,” Little said in the statement. “The new actions directed by Secretary Panetta today, in addition to the many steps taken by department personnel in recent months, are aimed at ensuring that the department upholds the important requirement to safeguard America's national security secrets.”

A separate Defence Department document obtained by The Associated Press spells out the steps the Pentagon has taken to reduce the unauthorised disclosure of classified information. Among the 10 steps were better training of Pentagon personnel if they suspect a threat from an insider or observe a leak, clearer instructions on what constitutes a leak and an online reporting system for significant security incidents.

The document also said that the undersecretary of Defence for intelligence commissioned a working group in April 2012 to develop a strategy to prevent leaks.

The House Armed Services Committee chairman, speaking after the closed briefing, said he did not believe the Pentagon was responsible for recent national security leaks.

“I feel pretty secure they were not” from the Pentagon, California Republican Rep. Howard “Buck” McKeon, told reporters after the three-hour hearing.

McKeon would not say where he believed the leaks came from, but some Republicans have speculated that the White House was responsible for the leaks to enhance President Barack Obama's national security image and improve his chances of re-election. They have demanded a special counsel, removing an investigation of the leaks from two US attorneys selected by Attorney General Eric Holder.

The chairman said the officials “assured us they are proceeding to try to limit those leaks,” adding that the leaks have “the potential for causing serious harm.” He said all three officials agreed that the leaks have already damaged national security. The top Democrat on the committee, Rep Adam Smith of Washington state, said he also was convinced the Pentagon was taking the issue seriously.

Holder has appointed US Attorneys Ron Machen in the District of Columbia and Rod Rosenstein, who is based in Baltimore, to lead the investigation into who leaked information about US involvement in cyberattacks on Iran and about an al-Qaeda plot to place an explosive device aboard a US-bound flight.

Holder said the investigation is moving fast, and added that he and FBI Director Robert Mueller had already been interviewed.

That didn't satisfy Republicans, who demanded that the probe not be conducted by US attorneys who work for the Justice Department.

Republican John McCain has called the leaks an “almost unprecedented release of information which directly affects our national security. I can't think of any time that I have seen such breaches of ongoing national security programs as has been the case here.”

Holder contended the Obama administration has brought more leak prosecutions than any other administration and has charged six people under the Espionage Act for the alleged mishandling of classified information. He added that speed in carrying out the leak probes was an important factor in appointing the two prosecutors. -