Allies prepare to send in their troops

The United States and Britain are preparing for a new, more dangerous phase of their military campaign against Afghanistan that will see ground forces unleashed against Osama bin Laden and his al-Qa'ida terrorist network.

As Allied forces carried out a third night of air strikes, the Pentagon claimed yesterday that it had virtually knocked out the Taliban's air defences, paving the way for the next phase and the deployment of additional American and British ground troops on the borders of Afghanistan.

"In the next week, you'll see people start moving," said one official. The planned deployment is expected to include the dispatch of a further 1,000 US troops to Uzbekistan, where 1,000 soldiers from the 10th Mountain Division have already arrived.

A large number of British troops are also expected to move to Uzbekistan, on the Afghan border, straight from military exercises in Oman.

Donald Rumsfeld, the US Defence Secretary, said 85 per cent of designated targets inside Afghanistan had been hit and US and British warplanes could operate around the clock with minimal risk.

General Richard Myers, the chairman of the US joint chiefs of staff, added: "Essentially we have air superiority over Afghanistan." These claims, backed by satellite photographs purporting to show the destruction of an al-Qa'ida training camp, a surface-to-air missile site and the runway at the important Shindand air base in west Afghanistan, make it likely the air-strike phase of the campaign will be wrapped up in a day or two.

The Americans' mastery of the Afghan skies will also open up for the first time the prospect of untrammelled surveillance of Mr bin Laden's possible hiding places.

But last night, the al-Qa'ida network released another taped statement in which Osama bin Laden's spokesman renewed calls for a holy war against American interests and praised the 11 September hijackers. The spokesman, Sulaiman Abu Gaith, in a recording broadcast by the Qatar-based Al-Jazeera network, made a direct threat of more terror attacks: "America must know that the storm [sic] of Afghanistan will not stop and there are thousands of young people who look forward to death in the same way as Americans look forward to life.''

With conventional military targets in Afghanistan virtually dealt with, the conflict is entering a new phase as the ground troops are preparing to go deep into hostile territory, sometimes in operations co-ordinated with the opposition Northern Alliance, now helped by extra Allied military and financial aid.

As the US and Britain kept up the pressure from the air, the Northern Alliance claimed that about 1,200 Taliban soldiers had defected, closing the only road linking north and south Afghanistan. If true, it would be a big success for Washington in its efforts to weaken the regime. The Northern Alliance claimed 40 commanders and their men had switched sides, leaving Kabul with only one, indirect supply route.

The "foreign minister" of the Northern Alliance, Abdullah Abdullah, said he believed the Taliban would fall "in a matter of weeks, perhaps, if not days".

With the Taliban air defences largely destroyed, US and British forces can now be flown in to seize bases in Afghanistan itself. Most desirable would be the all-weather air base at Bagram, 20 miles north of Kabul.

Military planners have taken care to avoid inflaming the situation in Pakistan, where anti-American feeling is running high in the wake of the US air raids that have pummelled Afghanistan since Sunday. Four pro-Taliban protesters, including a 13-year-old boy, were shot dead by police in the border town of Kuchlak yesterday.