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Brian Williams cancels his Letterman appearance

No Letterman appearance for Brian Williams while he's away from NBC Nightly News

Embattled NBC Nightly News anchor Brian Williams has pulled out of his scheduled Thursday appearance on "Late Show With David Letterman."

Williams did not feel he should keep his commitment to be a guest on the program when no determination has been made as to when he will return to NBC Nightly News, according to an NBC News executive not authorized to discuss the matter publicly.

Since no date for his return has been set, Williams wanted "Late Show" to have adequate notice to book another guest, the executive added.

RELATED: Brian Williams misremembers -- and the Internet won't let him forget it

Williams announced Saturday that he was taking a short leave from his program while the news division fact-checks his reporting on a U.S. military mission in the 2003 invasion of Iraq. Williams has apologized for wrongly saying he was in a Chinook helicopter that was forced down after being hit by enemy fire.

In 2013, Letterman's program was one of the forums where Williams gave the incorrect version of the incident in which another helicopter in the 159th Aviation Regiment was hit.

The anchor's 2005 reporting on Hurricane Katrina in New Orleans is also being examined after local media there pointed out possible discrepancies.

Williams said in a statement that he expected to be away from his broadcast for "the next several days" so he could "adequately deal with the issue." Lester Holt will fill in during his absence.

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