U.S. intelligence agencies have found no evidence that al-Qaida has sneaked any terrorists into the United States for a strike coinciding with the 10th anniversary of the Sept. 11 attacks, senior officials said Saturday.

    But authorities kept a high alert as investigators looked for proof of a plot possibly timed to disrupt events planned in Washington or New York.

    Since Sept. 7, counterterrorism officials have chased a tip that al-Qaida may have sent three men to the United States on a mission to detonate a car bomb in either city. At least two of those men could be U.S. citizens, according to the tip.

    No intelligence supported that tip as of Saturday, and officials continued to question the validity of the initial information.

    While such tips are common among intelligence agencies, this one received more attention, and government officials chose to speak publicly about it, because of the connection to the anniversary of the worst terrorist attack in U.S. history.

    (SD-Agencies)