WASHINGTON (AFP) - President Barack Obama named Energy Secretary Ernest Moniz as "designated survivor" should a catastrophic attack wipe out he and his Cabinet during his State of the Union address on Tuesday.

The practice of holding back one Cabinet member at an undisclosed location from the showpiece event is designed to ensure continuity of power in the event of a terror attack or other disaster.

Mr Obama, Vice-President Joe Biden, leaders of the House of Representatives and the Senate, Supreme Court Justices and top military officers all habitually attend the annual address on Capitol Hill.