WASHINGTON: President Barack Obama denied on Friday that the White House has deliberately leaked classified national security information that is flattering to him in this election year, calling such allegations ''offensive'' and ''wrong.''

He promised investigations into the source of leaks about US involvement in cyber-attacks on Iran and drone strikes on suspected terrorists.

''The notion that my White House would purposely release classified national security information is offensive,'' Obama said during a White House news conference. ''It's wrong.''

A few hours after Obama's comments, Attorney General Eric Holder appointed two US attorneys to lead a pair of criminal investigations into possible unauthorized disclosures of classified information.

Recent news articles have contained details of US involvement in a partially successful computer virus attack on Iran's nuclear program and on the selection of targets for counterterrorism assassination plots.

The leaked information generally paints Obama as a decisive and hands-on commander in chief, and Republican critics suggested the leaks were orchestrated to boost Obama's re-election chances.

Obama said his critics ''need to have a better sense of how I approach this office and how the people around me here approach this office.''

''We're dealing with issues that can touch on the safety and security of the American people, our families or our military personnel or our allies, and so we don't play with that,'' he said.

Obama said his administration has ''zero tolerance'' for such leaks and that there would be an internal administration probe.

In his statement, Holder said he had appointed Ronald Machen, the US attorney for the District of Columbia, and Rod Rosenstein, the US attorney for the District of Maryland, to direct separate probes being conducted by the FBI.

''We have mechanisms in place where if we can root out folks who have leaked, they will suffer consequences,'' Obama said. ''In some cases, it's criminal. These are criminal acts when they release information like this. And we will conduct thorough investigations, as we have in the past.''

Leaders of the Senate and House intelligence committees said on Thursday they were drafting legislation to further limit access to highly classified information and possibly impose new penalties for revealing it. The chairman of the House Intelligence Committee said he will investigate recent leaks.

Lawmakers have pointed to recent stories by The New York Times, The Associated Press and other news organisations that contain previously secret information and cite anonymous US officials.

The strongest claims came from Obama's 2008 election opponent, Republican Sen. John McCain.

''They're intentionally leaking information to enhance President Obama's image as a tough guy for the elections,'' McCain said Tuesday, after taking to the Senate floor to list some of the alleged breaches. ''That is unconscionable.''

McCain called on the administration to appoint an outside special counsel to investigate.

The House Intelligence Committee chairman, Rep. Mike Rogers, said his committee would formally investigate the leaks, but said he was concerned about the level of cooperation he would get from two government agencies.

''Just today, the CIA informed the (committee) that it cannot respond to our request for information regarding the leaks, a very troubling event indeed,'' Rogers said.

The CIA has come under fire for allegedly sharing with Hollywood filmmakers classified details of last year's US raid into Pakistan that killed Osama bin Laden.

A Justice Department official, who spoke on condition of anonymity to discuss sensitive information, said some officials in the department's national security division recused themselves from one of the leak probes but that the department overall was investigating.

There are at least three investigations ongoing into disclosures of classified information.