Bin Laden terror group boasted of 'Hiroshima' on US

The CIA intercepted a message from an al-Qaida member boasting of plans to carry out a "Hiroshima" on America, it was revealed today.

The message, last year, said Osama bin Laden was planning to carry out an attack like Hiroshima, a reference to the 1946 atomic bomb dropped on the Japanese port which killed more than 200,000 people.

But in spite of a frenzied search for evidence of what the message meant, American spies drew a blank and had no idea of the plans being laid for the September 11 attacks, according to reports.

And in another development in the investigation into the terror strikes on America, American officials are now examining whether ringleader Mohammed Atta not only led the attacks but came up with the daring plot.

Bin Laden’s al-Qaida organisation works by giving training and cash to fanatical Muslim groups - and letting them pursue their own plans.

The insight into how the group works has led investigators to come up with a new theory of how the attacks were planned.

American officials said it was possible Atta took his plan for co-ordinated suicide hijackings to bin Laden, who approved the plot.

Bin Laden then provided cash and logistical support, while messages between al-Qaida commanders and Atta were passed through intermediaries.

But investigators are struggling to confirm their theory, whereas in the 1998 twin bombings of the American embassies in Kenyan capital Nairobi and Tanzanian capital Dar-es-Salaam, informers and witnesses were found.

"Part of what is so hard is that so many of the key players are dead," an American official said.

"With the embassy bombings, there were key arrests. They made confessions, named names. We don’t have anything like that."

They have also found no evidence that any of bin Laden’s key henchmen travelled to America or Europe to co-ordinate the attacks.

Investigators believe the September 11 kamikaze strikes were overseen by bin Laden’s three chief lieutenants.

They are Muhammed Atef, believed to be bin Laden’s handpicked successor and the man with responsibility for terrorist and military training within al-Qaida.

Ayman al-Zawahiri, the head of Egyptian Islamic Jihad, and the man thought to be in charge of military operations inside al-Qaida is one of the other three.

And the final lieutenant is Abu Zubaydah, head of "external affairs", responsible for al-Qaida’s propaganda and finance wings.