Royal Marines are called in

The unannounced reinforcement of British special forces at Bagram airport in the past few days indicates that the Americans and British are planning to widen their operations to hunt down Osama bin Laden and break the remnants of his forces in Afghanistan.

A party of more than 40 Royal Marines and special forces has joined the 100 men from the Special Boat Service, and yesterday the US sent in two platoons from the 10th Mountain Division to form a rapidresponse team at Bagram. Two platoons from the 10th Mountain Division have been sent to Mazar-i-Sharif to form another response team.

A week ago it had been said that the 100 men of the SBS had been "hung to dry" at Bagram with nothing to do as the Jamiat-i-Islami forces had got to Kabul before them. The Jamiat spokesman Abdullah Abdullah told the SBS commandos to go away as they were "unwanted".

He then said that 15 could remain at the base. Abdullah Abdullah has now said at the UN peace talks in Bonn that an international stabilisation forces will be welcome, if the UN thinks it necessary. Allied special forces and the US marines at Kandahar are now building "forward mounting bases" from which helicopter-borne forces can set out on deep reconnaissance missions to find Bin Laden.

The Allies are preparing for a major battle for Kandahar in the next 10 days. It is the largest city still in Taliban hands, and the home of the movement's founder, Mullah Omar.

Pentagon sources indicate that Central Command in Tampa, Florida, is planning to deploy "a substantial force" - probably from the 101st Airborne Division, for the final battle for Kandahar. The 101, which is a helicopter "air cavalry" force, is particularly suited to scouring the mountains.

The flow of stories that the Saudi renegade has fled to the Tora Bora in the mountains of Nangahar have been so consistent that they are now widely believed to be part of a local Taliban disinformation campaign. There is strong circumstantial evidence, say local sources, that Bin Laden is with Mullah Omar inside Kandahar.

US and British officials are now expressing "cautious optimism" that they will be able to track down Bin Laden. The latest American surveillance equipment, including the powerful but never-tested Global Hawk unmanned spy plane, has exceeded all expectations, according to intelligence sources.