The head of US spying operations says the leaders of al-Qaeda have found a secure hideout in Pakistan from where they are rebuilding their strength. Pakistan's tribal areas along the Afghan border are considered to be safe refuge for top terror leaders.

The National Intelligence Director John Negroponte also said that as al-Qaeda was strengthening itself across the Middle East, North Africa and Europe there has been no immediate reaction from the Pakistani government. Pakistan claims itself to be one of the key allies of the US for hunting down Islamic terrorists

US officials have also said that they believe al-Qaida leader Osama bin Laden is taking refuge in the region, likely on the Pakistani side of the border.

Pakistan and Afghanistan share a 1,400-mile (2,250km) mountainous border which is extremely difficult to patrol. Taliban and al-Qaeda fighters are thought to be operating on both sides.