A U.S. airstrike on Pakistan village targeted al Qaeda's second-in-command, U.S. intelligence sources say, but Pakistani officials said Ayman al-Zawahri was not there and condemned the attack.

The strike near the Afghan border on Friday killed at least 18 people, including women and children, and three houses were destroyed, according to residents of Damadola village in Bajaur tribal area.

CIA-operated unmanned drones were believed to have been used in the attack, U.S. sources said. A Pakistani intelligence official said four missiles had been fired.

Pakistan condemned the airstrike.