Washington ? Federal investigators questioned President Bush for more than an hour Thursday as the investigation into the leak of a CIA operative’s name reached into the Oval Office.

The president was interviewed for 70 minutes by U.S. Atty. Patrick J. Fitzgerald, the head of the Justice Department investigation, and by members of his team. The only other person in the room was Jim Sharp, a private trial lawyer and former federal prosecutor hired by Bush, said White House press secretary Scott McClellan.

“The leaking of classified information is a very serious matter,” McClellan said, adding that the president repeatedly has said he wanted his administration to cooperate with the investigation. “No one wants to get to the bottom of this matter more than the president of the United States.”

Investigators want to know who leaked the name of Valerie Plame, an undercover CIA operative, to syndicated columnist Robert Novak last July. Disclosure of an undercover officer’s identity can be a federal crime.

Fitzgerald declined, through a spokesman, to comment on the Bush interview, but legal experts following the case said it could indicate the probe was nearing an end.

The investigation has been an embarrassment for a president who promised to bring integrity and leadership to the White House after years of Republican criticism of the Clinton administration.

Former Ambassador Joseph Wilson, who is married to Plame, has said he believed his wife’s identity was disclosed to undermine his credibility. Wilson denounced the Bush administration for claiming that Iraq, under Saddam Hussein, had tried to obtain uranium from the African nation of Niger. Wilson went to Niger for the CIA to investigate and he found the allegation to be highly unlikely.