The White House took issue on Thursday with a claim by syndicated columnist Robert Novak that President George W. Bush knows who the source is who leaked the identity of CIA operative Valerie Plame.

“I don’t know what he’s basing it on,” said White House spokesman Scott McClellan, declining to comment further.

Novak said Tuesday the public and the news media should be asking Bush about the source rather than reporters who received the information.

“I’m confident the president knows who the source is,” Novak told a luncheon in Raleigh, North Carolina, according to the Raleigh News & Observer. “I’d be amazed if he doesn’t.”

He added: “So I say, don’t bug me. Don’t bug (Washington Post reporter) Bob Woodward. Bug the president as to whether he should reveal who the source is.”

Novak has repeatedly declined to discuss his role in disclosing Plame’s identity. It was his column on July 14, 2003, that outed Plame and triggered an ongoing investigation into the leak.

Plame’s cover at the CIA was blown after her husband, former diplomat Joseph Wilson, accused the Bush administration of twisting prewar intelligence to support invading Iraq. Wilson said it was done to undercut his credibility.

The two-year investigation, which has reached into the highest levels of the White House, resulted in charges in October of perjury and obstructing justice against Vice President Dick Cheney’s chief of staff, Lewis “Scooter” Libby. Libby, who pleaded not guilty, has resigned from the administration.

Bush’s top political adviser and deputy chief of staff, Karl Rove, was told by prosecutors that he remained under investigation and could still be charged.