Tape shown of American hostage in Saudi Arabia

CAIRO (AP) - An Islamic Web site showed videotape Tuesday of blindfolded American hostage in Saudi Arabia. It said abductors threatened to kill the hostage within 72 hours unless al-Qaida prisoners are freed.

Paul Johnson, 49, of Stafford Township, N.J., was abducted Saturday by a group calling itself al-Qaida in the Arabian Peninsula.

The tape, which was first aired by CNN, showed his Lockheed Martin identification card. Johnson was employed by Lockheed Martin and worked on Apache helicopters.

A statement on the Web site said that the group gave Saudi authorities 72 hours to release "mujahadeen" militants or the hostage would be killed.

Earlier Tuesday, Saudi security forces arrested a militant north of Riyadh as they stepped up their presence in and around the city in a hunt for Johnson's kidnappers.

The day he was seized, Islamic militants shot dead another American, Kenneth Scroggs, from Laconia, N.H., in his garage. Scroggs was the third Westerner killed in a week, after the shooting death of an Irish cameraman for the British Broadcasting Corp. on June 6 and another American who was killed in his garage June 8.