US Vice President Dick Cheney made a surprise visit to Pakistan on Monday and held talks with President Pervez Musharraf on curtailing Taliban activities in Afghanistan.

Cheney arrived Monday morning and drove straight to Musharraf's office in Rawalpindi, south of the capital Islamabad. Officials said their talks focused on the situation in Afghanistan where the Taliban appeared to be digging in with the alleged support from Pakistan. The two also discussed the situation in the Middle-East, they said. The unscheduled trip coincides with the visit of British Foreign Secretary Margaret Beckett.

Meanwhile, US President George W Bush warned Pakistan President Pervez Musharraf that that the Democrats-dominated Congress could cut aid to Islamabad unless its forces become far more aggressive in hunting down operatives with Al Qaeda, The New York Times quoted senior administration officials as saying.

The newspaper said that the decision came after the White House concluded that Musharraf is failing to live up to commitments he made to Bush during a visit to Washington in September.

During his visit, Musharraf had assured that a peace deal he struck with tribal leaders will not diminish the hunt for the leaders of Al Qaeda and the Taliban or their training camps.

Intelligence officials believe that the terrorist infrastructure is being rebuilt, and that while Pakistan has attacked some camps, its overall effort has flagged, the report said.

'He's made a number of assurances over the past few months, but the bottom line is that what they are doing now is not working,' one senior administration official was quoted as saying.

Democrats, who took control of Congress last month, have urged the White House to put greater pressure on Pakistan because of statements from American commanders that units based in Pakistan that are linked to the Taliban, Afghanistan's ousted rulers, are increasing their attacks into Afghanistan, the report said.

The report also quoted officials as saying that for the time being, the White House has ruled out unilateral strikes against the training camps that American spy satellites are monitoring in North Waziristan.

The spread of al Qaeda in the tribal areas threatens to undermine a central element of Bush's argument that he is succeeding in the administration's effort to curb terrorism. The bomb plot disrupted in Britain last summer, involving plans to hijack airplanes, has been linked by British and American intelligence agencies to camps in the Pakistan-Afghan border areas.