The claim, from the terrorist group led by the fugitive Jordanian Abu Musab al-Zarqawi, came in an internet statement identifying all four bombers as Iraqis.

It said that one was the wife of a suicide bomber who had chosen to die alongside her husband. “The group charged with planning, preparing and implementing [the bombings] was made up of three men: commanders Abu Khabib, Abu Muaz and Abu Omaira. Their fourth was the venerable sister Umm Omaira,” the statement said. The wife of Abu Omaira “chose to accompany her husband to his martyrdom”.

If this is true, it would be the first known case of a husband and wife suicide bomber team.

Senior Jordanian intelligence officials denied that there had been a female bomber and said that they had recovered the bodies of three male bombers. There was no reason to believe that any of the other unidentified dead were also bombers.

It emerged yesterday that one of the 57 victims was Mustapha Akkad, the producer of the Halloween horror films, and one of few Arabs to have succeeded in Hollywood.

Mr Akkad, 68, emigrated to America at the age of 19 but remained an Arab at heart and was often critical of the way Muslims are depicted in American movies. “In Hollywood, Muslims are only terrorists,” he said in a New York Times interview in 1998.

Mr Akkad was also known for producing the Oscar-nominated epic The Message: The Story of Islam and The Lion of the Desert funded by the Libyan leader Colonel Muammar Gaddafi. Mr Akkad’s daughter Rima, 33, also died in the blast.

According to the al-Qaeda statement, the bombers used “suicide belts for precision and to cause maximum damage”. It claimed that “the attackers managed to enter the targets bypassing all the security measures that the agent of the British, the treacherous Abdullah, has always boasted about” — a reference to the Jordanian king, the son of his father’s British first wife.

More than 120 people, including Iraqis and Jordanians, were questioned by the police yesterday but only 14 remained in custody last night for further investigation. Many of those detained in the sweep were rounded up from a poor neighbourhood populated by Iraqi workers but police refused to give the nationalities of the suspects as investigations continued into various underground cells.

Jordan sealed its border yesterday against all outgoing traffic to Iraq to prevent any suspects fleeing. The news came as King Abdullah II attended prayers at al-Hashimiyah mosque in another part of the city, where the imam denounced the bombers as ignorant people whose actions were totally banned by Islam.

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