An Islamic Web site showed videotape Tuesday of a blindfolded American hostage in Saudi Arabia and said abductors had threatened to kill him within 72 hours unless Saudi authorities free al Qaeda prisoners.

Paul Johnson, 49, of Stafford Township, N.J., was abducted Saturday by a group calling itself al Qaeda in the Arabian Peninsula. The organization is believed to be headed by al Qaeda's leader in Saudi Arabia, Abdulaziz Muqrin.

A hooded man read a statement on the tape. A subtitle on the screen identified him as Muqrin.

His statement was similar to a printed message on the Web site that carried the name al Qaeda in the Arabian Peninsula. It said the group gave Saudi authorities 72 hours to release mujaheddin militants or it would kill the hostage.

The tape, which was first aired by CNN, showed Johnson sitting in a chair with his profile to the camera, a large tattoo on his left arm. The tape also showed his Lockheed Martin Corp. identification card. Johnson was employed by Lockheed Martin and worked on Apache helicopters.

Adel Jubeir, foreign affairs adviser to the Saudi government, said shortly after the video appeared that the kingdom would consult with the Bush administration about how to proceed. Riyadh like Washington has a strict no-negotiation policy.

"We don't negotiate with terrorists," Jubeir said in an interview on CNN.

The statement on the Web site says the holy warriors of the Arabian Peninsula's Fallujah Brigade have "hit" the engineering team that "oversees the development of the American Apache helicopter that attacks Muslims in Palestine and Afghanistan."

It says: "The Fallujah Brigade has killed the director of this team and kidnapped one of its engineers, Paul Johnson, and if the tyrannical Saudi government wants their American master to be released, then they have to release our holy warriors that are held in Hair, Ruweis and Alisha prisons within 72 hours of this statement's date."

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.