Can't confirm bin Laden tape authentic: White House

WASHINGTON (Reuters) - A White House top adviser said on Sunday he could not confirm the authenticity of an audiotape purported to be Osama bin Laden claiming responsibility for the December 25 attempted bombing of a U.S.-bound plane.

"I can't confirm that (al Qaeda's responsibility for the attack) nor can we confirm the authenticity of the tape, but assuming that it is him, his message contains the same hollow justifications for the mass slaughter of innocents that we've heard before," David Axelrod said on CNN's "State of the Union" program.

The audiotape that aired on Al Jazeera television on Sunday claimed responsibility for the attempted Christmas Day bombing of the Detroit-bound plane. A Nigerian, Umar Farouk Abdulmutallab, has been charged with trying to blow up Northwest Flight 253.

"The message sent to you with the attempt by the hero Nigerian Umar Farouk Abdulmutallab is a confirmation of our previous message conveyed by the heroes of September 11," the voice purported to be bin Laden said on the tape.

Axelrod said of bin Laden: "The irony is that in the name of Islam he's killed more Muslims than people from any other religion. He's a murderer and we're going to continue to be on the offense against bin Laden, against al Qaeda, to protect the American people."

(Reporting by Vicki Allen; Editing by Peter Cooney)