Portions of the tapes, recorded from 1998 to 2000 by author Doug Wead without Bush's knowledge, were aired on ABC News on Sunday and published by The New York Times. Their authenticity was verified by the media outlets.

"I wouldn't answer the marijuana question. You know why? Because I don't want some little kid doing what I tried," Bush purportedly says on the tape.

He added: "But you got to understand, I want to be president. I want to lead. I want to set -- Do you want your little kid say, 'Hey, Daddy, President Bush tried marijuana, I think I will?"'

Bush mocked former Vice President Al Gore -- who fought him for the presidency in 2000 -- for admitting he smoked marijuana, saying the admision was "a foolish move."

White House officials did not dispute the tapes' veracity and indicated the president was disappointed by their release.

"These were casual conversations that then Gov. Bush was having with someone he thought was a friend, and that's what they are," White House spokesman Scott McClellan told reporters traveling with Bush to Europe aboard Air Force One.

McClellan said Bush, who was governor of Texas when the tapes were made, was not aware he was being recorded and the White House found out only when contacted by the New York Times for comment.

"Look, I think that, one, the comments in the tapes speak for themselves. And two, I think that what I just said pretty much speaks for itself," McClellan said when pressed about the details.

"Those were issues that were addressed ad nauseam four years ago and they were conversations that took place more than four years ago," he said, adding that Bush had not been in contact with Wead for several years.

Wead, a former aide to Bush's father President George H.W. Bush, released portions of the tapes to coincide with the publication of his new book and told ABC he made the tapes because he believed the president was an historic figure.

"If I'd had a chance to tape record Gandhi or had conversations with Churchill, I probably would have recorded them too," he said.

He also insisted his goal was not to hurt the president's credibility and said if this were the case he would have released the tapes during the 2004 election campaign.

Asked about the tapes in an interview with CNN, the president's father said he was not aware of them and declined comment.

Sitting next to Bush was ex-President Bill Clinton, who admitted to smoking marijuana when he campaigned for the White House but said he never inhaled the illegal drug.

The two former presidents are touring areas affected by the Dec. 26 Indian Ocean tsunami.