Bin Laden 'leading 1,000 fighters' at mountain lair

Osama bin Laden is thought to be leading around 1,000 al-Qaida fighters in defending his mountain stronghold of Tora Bora.

Meanwhile, a small UN team is in Kabul paving the way for the deployment of an international peacekeeping force.

The technical team from the UN's department of peacekeeping operations are assessing whether security conditions are stable enough.

They hope to introduce thousands of troops in a so-called "coalition of the willing".

US Secretary of State Colin Powell has suggested that Britain is one of the most likely candidates to lead the peacekeeping force.

The Ministry of Defence says that no request for troops has yet been received.

The UK had made clear from the outset of the Afghan conflict its willingness to make a "significant contribution" to any multinational force.

UN spokeswoman Wivina Belmonte says the size and make-up of any eventual military force has not been finalised.

She added that the Kabul detachment would be joined by another seven experts currently in Islamabad, but gave no indication of the timetable for the introduction of peacekeeping troops.

The deployment of a multinational force was agreed at last week's summit of Afghan ethnic groups in Bonn, Germany, which set up an interim government headed by Pashtun warlord Hamid Karzai.