US President George W Bush is under pressure from Democrats to reveal if he was behind the leaking of Iraq secrets.
Court papers cite an ex-official as saying he had been told he had Mr Bush's authorisation to discuss classified material with journalists.
The White House says any information released was done "in the public interest", arguing the president has the power to declassify information.
The ex-official, Lewis Libby, is facing trial in a separate CIA leak case.
He is accused of obstructing an investigation into the leaking of a CIA agent's identity.
Mr Bush - who is not accused of authorising the release of the agent's name - has in the past condemned leaks and has said he would sack anyone involved.
The president's supporters say even if Mr Libby's testimony is accurate, what the president is alleged to have done does not constitute a leak because Mr Bush had the authority to release the information.
But the BBC's Justin Webb in Washington says President Bush is once again fighting for his political credibility, with Democrats smelling blood.
Mr Libby said he was told in July 2003, when he was chief-of-staff to Vice-President Dick Cheney, to give a reporter pre-war intelligence, court papers reveal.
CIA LEAK TIMELINE
6 Jul 2003: Joseph Wilson questions US claims about Iraq nuclear programme
8 Jul: Libby leaks classified information to reporter Judith Miller, but not agent's name, he later testifies
14 Jul: Columnist Robert Novak identifies Wilson's wife as CIA agent
30 Sept: Justice dept launches inquiry into agent's outing
28 Oct 2005: Libby charged with obstruction and perjury
6 Apr 2006: Court papers suggest Bush authorised leak of classified material (not agent's identity)
He testified that Mr Cheney had told him to pass information from the classified National Intelligence Estimate to Judith Miller, a New York Times reporter.
Mr Cheney is alleged to have said that the release of classified information had been approved by the president.
Mr Libby said he understood this meant he had legal cover to discuss this material.
Top Senate Democrat Harry Reid called the claim "shocking", and said Mr Bush "must fully disclose his participation in the selective leaking of classified information".
Congresswoman Jane Harman, the senior Democrat on the House's intelligence committee, said: "If the disclosure is true, it's breathtaking. The president is revealed as the leaker-in-chief."
CIA leak row
The aim of the leak, Mr Libby is reported to have said, was to rebut an article questioning some of the evidence used to justify the case for a US-led invasion of Iraq.
The article was written by former diplomat Joseph Wilson, the husband of the undercover agent Valerie Plame who was subsequently outed.
Court papers quote Mr Libby as saying he did not discuss Ms Plame during his 8 July 2003 meeting with Miller.
Mr Libby is charged with lying to investigators and obstructing the investigation into the leak of Mrs Plame's identity.
He resigned as chief-of-staff to Mr Cheney after he was charged last year and is due to go on trial in January 2007.
No-one has been charged with a crime over the leaking of Mrs Plame's name to reporters.