Osama bin Laden remains deeply isolated and has been forced to devote much of his energy to his own security, CIA Director Michael Hayden said in a speech on Thursday.

Hunting down bin Laden remains a high priority for the Central Intelligence Agency, he said.

"I can assure you, although there has been press speculation to the contrary, I can assure you that the hunt for bin Laden is very much at the top of CIA's priority list."

He suggested that bin Laden was hiding somewhere in the remote Afghanistan-Pakistan border region, where he said Al-Qaeda has regrouped and bolstered its organization.

He said major terrorist threats against the United States could all be traced back to the group's "safe haven" in the tribal areas of Pakistan.

Al-Qaeda was on the retreat in Saudi Arabia, Indonesia, the Philippines and Iraq, while it had strengthened in Pakistan's tribal areas and expanded its activity into North Africa, Somalia and Yemen.