'What we have to consider is what happens when the foreign troops leave Afghanistan. If the Taliban then take over, we don't want to be on the wrong side,' another said.

The paper said US requests for Pakistan to end Taliban sanctuaries were conveyed last week during a visit to Islamabad by Gen. Stanley McChrystal, the commander of US and Nato forces in Afghanistan, and General Karl Eikenberry, the US ambassador to Kabul.

It was reinforced by US President Barack Obama's special envoy Richard Holbrooke, who is visiting the region.

With the Swat Valley almost cleared after three months of fighting and Pakistani troops moving into the border areas of Waziristan to pursue Baitullah Mehsud, leader of the Pakistani Taliban, there is concern that Islamabad seems to have no interest in taking on militant groups that are using its territory to attack western forces over the border, the newspaper said.

A senior US official said: 'We still don't see any evidence that Islamabad has politically or militarily made a decision to go after the Afghan Taliban.'

McChrystal said last week: 'What I would love is for the government of Pakistan to have the ability to eliminate the safe havens that the Afghan Taliban enjoy.'