Iraq's estimated 60 surface-to-air missiles, or SAM, batteries have proved hard to find and hard to hit. ``They are moving their batteries around quite heavily'' now from one launch site to another, the official said yesterday, speaking on condition of anonymity.

The increased shifting in the missile sites comes as Iraq twice this week tried to shoot down US and British aircraft patrolling no-fly zones in Iraq.

American fighter jets destroyed two of the Iraqi missile sites on Monday and Wednesday by firing radar-seeking missiles and laser-guided bombs. The action responded to attempts by Iraqi President Saddam Hussein's military to strike US and British warplanes with missiles. US planes aimed at smoke and dust plumes immediately after the Iraqi missiles werelaunched and locked onto the brief Iraqi radar used in the attacks.