The mastermind of the September 11 attacks has told US interrogators that he first discussed the plot with Osama bin Laden in 1996, according to interrogation reports.

Clues filtering in from around the world since at least 1994 foreshadowed Osama bin Laden’s plans to attack the US, and intelligence information from Italy, Israel and elsewhere before September 11 warned that a terrorist strike might be imminent.

US officials received a warning in 1995 that Islamic militants were plotting to attack an American nuclear site and targets in Britain - but did not pass on the information to the agency overseeing nuclear facilities or to the plants themselves, it has emerged.