ABC News aired a videotape last night of a purported American member of al Qaeda declaring that a new series of terrorist attacks against the United States could come "at any moment."

The network, which has held the tape since Monday while it tried to authenticate it, acted after being told by the CIA that the video bears "all the trademarks of an al Qaeda production," as reporter Brian Ross explained. Federal investigators do not know the identity of the man on the tape, but copies are going to 13 current and former officials named during the 75-minute video.

Officials have been unable to match the speaker's voice to any known al Qaeda supporter or sympathizer.

The speaker, face obscured by a headdress and identified only as "Azzam the American," says on the videotape: "No, my fellow countrymen, you are guilty, guilty, guilty, guilty. You are as guilty as Bush and Cheney. You're as guilty as Rumsfeld and Ashcroft and Powell."

The man continued: "After decades of American tyranny and oppression, now it's your turn to die. Allah willing, the streets of America will run red with blood, matching drop for drop the blood of America's victims." The man speaks in accented English, pronouncing, for example, "tyranny" as "tie-ranny."

He also makes references to comedian Bill Maher, who once said that suicide attackers were less cowardly than long-distance cruise missile launchers, and Sept. 11 commission Chairman Thomas H. Kean (R). The man also criticizes Muslims who have lost their faith. "September 11 was but the opening salvo of the global war on America," he says.

A U.S. counterterrorism official told The Washington Post that intelligence analysts are still examining the tape. It has been judged to be of professional quality, and the speaker is considered to be college-educated and probably raised or schooled in the United States, the official said.

ABC executives were frustrated that after holding the tape and working closely with federal officials to authenticate it, Fox News obtained and aired a copy about 20 minutes before it was shown on Peter Jennings's newscast last night.

Staff writer Susan Schmidt contributed to this report.