Fittingly for a man who proved so slippery for Western intelligence agencies, bin Laden took up judo under the tutelage of Jimmy Wu, who was the Saudi national coach from 1981 to 1991.

To back his claims, Mr Wu has released pictures of himself alongside a tall, thin, studious-looking young man wearing a judo suit. The photos have not been verified but bear a passing resemblance to bin Laden when he was young.

Mr Wu said that bin Laden, who stood 6ft 4ins, was too tall to be a good judo player, and advised him against the sport. However, he accepted him for instruction after bin Laden insisted. "I didn't know the name bin Laden then," Mr Wu said. "After 9/11, I was invited to a seminar, and some of my former students there said, 'Oh Jimmy, Osama, now he's our hero'. I was surprised and I looked for some pictures and I said, 'Oh this guy,' and I started to have some memory of him."