US intelligence officials are investigating two videotapes threatening to unleash more terror attacks against the United States, in hope of finding clues that could help locate the speakers, media reports said Sunday.

In a videotape broadcast by ABC News on Thursday, a man claiming to be an American operative of al Qaeda threatened terror attacks "at any moment." The man delivered his message in English and his face was covered with a headdress.

Video clips of the man have been posted on the Federal Bureau of Investigation's (FBI) Web site. The FBI was urgently seeking information on the person's identity and that he might be living outside the United States, the posting said.

"We hope you might recognize him from his voice, his body language, or the style and content of his speech," the FBI posting said.

The second tape - of al Qaeda leader Osama bin Laden - was broadcast Friday by the Qatar-based Arabic-language TV network Al-Jazeera. The tape was reportedly received by the US Embassy in Qatar before it was made public.

The videotape appeared to be authentic and recently made, according to US officials.

President Bush instructed top homeland and national security advisers Saturday to "take all actions that might be necessary" to respond to the new message from bin Laden, the White House said.

Despite of the video tapes, Homeland Security Tom Ridge said it was safe to vote Tuesday. There was no actionable intelligence in the tapes to warrant raising the threat level, he said.

"There's no specific intelligence that targets election day, polling places, and the like," he said.