US military and intelligence officials are using powerful software called Analyst's Notebook and have engaged the services of Task Force 121, which also helped in Saddam Hussein's capture, to arrive at a clear picture of Osama bin Laden's whereabouts.   

Key to the search is 'accumulated humint', or human intelligence, a media report said, adding the software used in the search helps piece together data on criminal and terror networks.

Quoting officials, Newsweek magazine said an increasing number of 'data points' -- reports of sightings -- have created an ever-clearer picture of bin Laden's area of operation as he appears to shuttle between Pakistan and Afghanistan. 

Now they've focused that to the point where they have been able to send in Predator unmanned aerial vehicles to search for him.

The man charged with finding bin Laden, the news magazine said, is former Navy SEAL and current Rear Admiral William H. McRaven. He is heading up Task Force 121, a covert, miniature strike force with a command structure so secretive that McRaven's role hasn't even been reported until now.     

As bin Laden apparently no longer dares to use electronic means of communication, for fear that the US would be listening, McRaven and his hunters are now trying to snare his couriers in transit, the report said.

They scored a major victory two months ago with the capture of Hassan Ghul, a Qaeda operative who was carrying what US officials say was a strategic memo from Abu Mussab al-Zarqawi, the mysterious terror leader allegedly behind the bombings of Shiites in Iraq.

Task Force 121, which also helped to capture Saddam Hussein under McRaven's command, represents something brand new in warfare, a pure hybrid of civilian intelligence and military striking power, reports the magazine.

It is the most ambitious melding yet of CIA assets, Special Forces (mainly the Army's Delta Force) and the Air Force.

Formed late last year as part of Joint Special Operations Command -- the secret "black ops" under Major General Stanley McChrystal, who until recently was deputy operations director of the Joint Chiefs of Staff -- it is designed to produce a lightning-fast reaction should intelligence locate bin Laden or any other 'high-value targets' anywhere for a few hours, Newsweek reports.

Within the past few weeks, the magazine quoted intelligence sources as saying a US Predator also spotted a suspect believed to be Al-Zawahiri somewhere in the border area.

A Taliban official in Pakistan, contacted by Newsweek, said he's heard that both top Qaeda leaders moved to more secure and separate locations in January, weeks before the spate of publicity about an American 'spring offensive'.

The Taliban official said he learned that from a ranking Qaeda operative, a Yemeni who told him that other Qaeda and Taliban fighters had moved into Afghan provinces more than 150 kilometres from the Pakistani border.

"We decided to leave the dangerous zone for safer areas," the Arab told the Taliban official, Zabihullah. "The sheikh is now in the most secure area he has ever been in," the Arab said, referring to bin Laden.