New York ? CBS News apologized Monday for a “mistake in judgment” in its story questioning President Bush’s National Guard service, claiming it was misled by the source of documents that several experts have dismissed as fakes.

The network said it would appoint an independent panel to look at its reporting about the memos. The story has mushroomed into a major scandal, threatening the reputations of CBS News and chief anchor Dan Rather.

It also has become an issue in the presidential campaign. The White House said the affair raises questions about the connections between CBS’s source, retired Texas National Guard officer Bill Burkett, and Democrat John Kerry’s campaign.

Rather joined CBS News President Andrew Heyward in issuing an apology Monday. “We made a mistake in judgment, and for that I am sorry,” Rather said. “It was an error that was made, however, in good faith and in the spirit of trying to carry on a CBS News tradition of investigative reporting without fear or favoritism.”

Almost immediately after the story aired Sept. 8, document experts questioned memos purportedly written by Bush’s late squadron leader, Lt. Col. Jerry B. Killian, saying they appeared to have been created on a computer and not on the kind of typewriter in use during the 1970s.

CBS strongly defended its story. It wasn’t until a week later — after Killian’s former secretary said she believed the memos were fake — that the news division admitted they were questionable.

Burkett admitted this weekend to CBS that he lied about obtaining the documents from another former National Guard member, the network said. CBS hasn’t been able to conclusively tell how he got them, or even definitely tell whether they’re fakes or not. But the network has given up trying to defend them.

“Based on what we now know, CBS News cannot prove that the documents are authentic, which is the only acceptable journalistic standard to justify using them in the report,” Heyward said. “We should not have used them.”

Burkett, in an interview with Rather aired on the “CBS Evening News,” said he was pressured by CBS to reveal his source for the documents, and “I simply threw out a name that was basically, I guess, to get a little pressure off for the moment.”

He said he didn’t fake or forge any documents. “I didn’t totally mislead you,” he said. “I did mislead you about one individual.”

The report was a damaging blow to Rather, 72. Some have suggested the scandal could hasten his retirement.

But one of Rather’s most prominent colleagues said the anchorman’s job is not in jeopardy. “Everybody makes mistakes; there’s no talk of resigning,” John Roberts said. “Dan is the face of CBS News. We’re all behind him 100 percent.”