WASHINGTON, Sept 9 (Reuters) - President George W. Bush's homeland security adviser said on Sunday al Qaeda leader Osama bin Laden is "virtually impotent" and can do little more than send videotaped messages.

Top White House aide Fran Townsend said U.S. officials were studying bin Laden's new video tape for clues to his health or whereabouts, and whether there were any hidden meanings or messages.

But she said there was no sign of an imminent attack.

"This is a man on the run in a cave who is virtually impotent other than his ability to get these messages out," Townsend said on CNN's "Late Edition." "It is propaganda.

"Based on our experience, we have never seen bin Laden use a tape to trigger any operational activity."

Bin Laden made his first video appearance in nearly three years in a new tape released on Friday ahead of the sixth anniversary of al Qaeda's Sept. 11 attacks on the United States.

Townsend said information from the bin Laden tape was being shared with U.S. agencies both domestically and overseas.

U.S. terrorism monitoring firm IntelCenter said on Sunday it had early indications that a second bin Laden message would be released in coming weeks.

It said the next message was to be an audio statement addressed to Muslims around the world, although there had not yet been a formal announcement by as-Sahab, al Qaeda's media arm.

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