'We haven't seen Bin Laden since Tora Bora - we were distracted by Iraq, ' U.S. admits

U.S. officials have admitted that they have been forced to change tactics in their hunt for Osama Bin Laden because there has been no sighting of him for nearly seven years.

The Al Qaeda leader was last seen escaping from the CIA after the Battle of Tora Bora in Afghanistan in December 2001.

But as America today marks the seventh anniversary of the 9/11 attacks, U.S. forces admitted they were as far as ever from catching the 51-year-old Saudi-born terror leader.

The CIA claimed that the U.S. has so alienated tribesmen believed to be protecting Bin Laden that they have abandoned hope of tracking him down by diplomatic means.

The intelligence chiefs also said they are convinced Bin Laden is still hiding in the Pakistan mountains bordering Afghanistan.

It is thought he regularly wears disguises, avoids mobile phones and emails, and relies on human couriers to pass on messages.

Now focus will shift to the unmanned but lethal Predator drone spy plane, American media has reported.

And officials are aware of what they claim are their mistakes in the hunt: an over reliance on military force, the distraction of the war in Iraq, and a consistent underestimation of the enemy.

"Unless you have people who support you, human intelligence will never work," said Ali Muhammad Jan Aurakzai, a retired Pakistani general who oversaw efforts to track Bin Laden and other al-Qaeda leaders after 2001.

"You have to have friendly people."

The other major obstacle to the search was the war in Iraq, with officials from the CIA and the U.S. military saying they began shifting resources out of Afghanistan early in 2002 - and they still have not recovered from that mistake.

"Iraq was a fundamental wrong turn," John Brennan, a former deputy executive director of the CIA and a former chief of the National Counter-terrorism Centre, told American media.

"The collective effort in the government required to go after an individual like Bin Laden - the Iraq campaign consumed that."

But there are doubts about the switch in tactics.

American forces are unable to operate freely in Pakistan, meaning the search - led by the Predator drones - is taking place mostly from the air.

The Predators have launched their Hellfire missiles against four targets in the past month alone, killing two al Qaeda leaders since January.

But they are also killing civilians and straining diplomatic relations, and the approach may not be sustainable in the long-term.

"Making more effort and flailing are different things," a senior Pakistani security official told American media.