US and British special forces have been in Afghanistan for two weeks searching for Osama bin Laden, according to a newspaper report.
Unidentified senior US and Pakistani officials are quoted in USA Todayas saying commandos arrived in Pakistan on September 13th - two days after the attacks - and began moving into Afghanistan to capture or kill bin Laden or pin him down until the United States can launch air strikes.
Pentagon spokeswoman Ms Victoria Clarke refused to comment on the front-page story. Officials have said the US "war on terrorism" would be an unconventional battle in which commandos could play a key role.
The report, citing Pentagon officials in Washington and Pakistani military officials, says US special operations forces had landed in the Pakistani cities of Peshawar and Quetta.
Teams of three to five soldiers, supported by Black Hawk MH-60K helicopters based outside Afghanistan, focused their searches in caves and underground bunkers in southwest Afghanistan near Kandahar.
The report says the elite troops were having trouble finding bin Laden and had asked other nations for intelligence help.
Quoting US officials, it said several elite military units were involved in the effort to find bin Laden, including the US Army's Green Berets, Navy SEALS and the British Army's Special Air Services.