Fears of civil conflict in Pakistan rose on Monday amid reports that Osama bin Laden, prime suspect in the September 11 attacks on the US, had called on Pakistan's Muslims to resist "American crusaders from invading Pakistan and Afghanistan".

The call, reported by Qatar's al-Jazeera television, came as a US military liaison team was in Pakistan to begin detailed planning for an expected attack on the forces of Mr bin Laden and his Afghan protectors.

There was no independent confirmation on whether the statement was authentic, but the Qatar satellite station has interviewed Mr bin Laden in the past.

Senior Pentagon officials met their Pakistan counterparts in Islamabad on Monday to hammer out Pakistan's precise role in the widely anticipated military operation against Afghanistan.

The talks, which coincided with Pakistan's decision on Monday to withdraw its remaining diplomats from Afghanistan for security reasons, are understood to have focused on just how far Pakistan is prepared to get involved in any military action against its neighbour and former ally.

A senior Pakistan official said that Islamabad, which has offered the use of Pakistan airspace to US forces, maintained its objection to hosting any "visible US military presence" in the country, although it has agreed to provide logistical support to US-led ground forces.

However, Pakistan's Inter-Services Intelligence, Islamabad's equivalent of the CIA, is understood to be providing all the information it has on Afghanistan's military capabilities and the terrorist networks to which it plays host. Most of Afghanistan's terrorist training camps are in the south of the country in regions close to the country's border with Pakistan.

"General Musharraf [Pakistan's president] has repeated to myself and others that he would be unwilling for Pakistan to host any visible US military presence for internal stability reasons," said Khalid Mahmud, at the Institute of Regional Studies in Islamabad. "However, there is plenty of scope for providing a strong Pakistan role in providing logistical support to US forces."

The Pakistan government has attached three conditions to its support for US military operations against the neighbouring Taliban regime, say officials. First, it will not deploy Pakistan troops beyond the country's borders in Afghanistan or elsewhere. Second, any US military action against Afghanistan should be sanctioned by the United Nations Security Council in New York. And third, Pakistan should not be the launchpad for any ground force invasion of Afghanistan.

Pakistan's military regime is also increasingly anxious about the role that India, its neighbour and fiercest rival, would play in the multinational coalition against terrorism, say officials. Gen Musharraf has repeatedly told senior generals and leading opinion makers that Pakistan would lose ground to India in its longstanding struggle to gain sovereignty over the province of Kashmir if it failed to provide full cooperation to the US.

Jaswant Singh, India's foreign minister, and L.K. Advani, its home minister, have both sought to persuade the US that the Pakistan-based "jehadi" groups that operate across the line of control in Indian-held Kashmir should be classified as "terrorist" outfits. India was quick to offer naval and air facilities to the US after the terrorist outrages on 11 September.

"Pakistan faces a serious diplomatic threat from India if the Americans perceive that we are not fully cooperating with action against Afghanistan," said a senior official in Islamabad. The US military delegation is expected to stay on in Islamabad on Tuesday for further talks.