ABC News on Thursday broadcast a videotape it obtained last week of an English-speaking man who threatens bloody new al Qaeda attacks on the United States, but the network said US intelligence officials could not authenticate the man's voice.
"US intelligence officials say while they still cannot authenticate the voice on the tape, it has all the trademarks of an al Qaeda production," ABC News said.
It said the voice of the speaker, identified as "Assam the American," did not match that of any known American al Qaeda suspects.
But ABC said the US government was taking the tape seriously and had given copies of it to 13 current and former US officials mentioned by the speaker. These included US President George W. Bush and Vice President Dick Cheney.
The tape was broadcast with five days left in a US election campaign in which the battle against global terrorism has been one of the biggest issues between Bush and Democratic challenger Senator John Kerry.
ABC obtained the tape over the weekend in Pakistan, and its existence was revealed on Wednesday by Internet columnist Matt Drudge. ABC said on Wednesday that it would be "beyond irresponsible" to broadcast the tape without first authenticating it.
Network spokesman Jeffrey Schneider, asked why ABC broadcast the tape on Thursday, said, "The government is clearly taking this tape very seriously. They have distributed it to 13 current and former federal officials, and the CIA believes that the tape bears all the signatures of al Qaeda tapes we've seen in the past."
In the portions of the tape shown by ABC, the speaker, whose face is cloaked and who has a slight accent, says he is a follower of al Qaeda leader Osama bin Laden. He denounces Americans as "guilty, guilty, guilty."
"You are as guilty as Bush and Cheney," he said.
The speaker vows new attacks worse than the September 11, 2001, attacks on the United States. "After decades of American tyranny and oppression now it's your turn to die. Allah willing, the streets of America shall run red with blood matching drop for drop the blood of America's victims," he said.
A US intelligence official told Reuters on Wednesday that the film appeared to have been released by al Qaeda's media organisation and contains the logo of an al Qaeda production group. The official called the tape's content "classic al Qaeda propaganda" but said it appeared to have been edited.
The video appears to have been made as recently as late summer because the speaker discusses the Darfur conflict, makes a reference to the Massachusetts same-sex marriage legislation, and mentions the September 11 Commission, the intelligence official said.
Besides Bush and Cheney, other US officials mentioned in the tape include former CIA Director George Tenet, FBI director Robert Muller, and Attorney General John Ashcroft, government sources said.