A convoy supplying Nato forces in Afghanistan drove through the Khyber Pass yesterday as Pakistan reopened the crossing for the first time since militants hijacked and looted 13 lorries last week.

About 50 vehicles carrying oil, food and military hardware made its way to the frontier from the northwestern city of Peshawar, escorted by 100 Pakistani soldiers and paramilitaries in vehicles mounted with heavy machineguns. The escorts had orders to shoot on sight.

Helicopter gunships patrolled overhead and 100 security personnel were deployed along the route through Pakistan's lawless tribal areas, where armed forces are fighting al-Qaeda and Taleban militants.

Another 450 lorries were stranded in Peshawar, where they have been waiting since last week, as Pakistani authorities reviewed security on the road to Afghanistan. "We're happy about the armed escort, but we have to get the other trucks moving," Shakirullah Afridi, the head of the PakAfghan Goods Transport Association, told The Times. "People are losing money."

Nato and US forces in landlocked Afghanistan have to import about 70 per cent of military and civilian supplies through Pakistan - one of the reasons it is a key ally in the War on Terror. After being shipped into the port of Karachi, some supplies are taken by lorry through the Chaman border post between the Pakistani province of Baluchistan and southern Afghanistan.

Because of the strong Taleban presence in southern Afghanistan, most supplies are driven across Pakistan, over the Khyber Pass and through the border town of Torkham to Kabul, the Afghan capital. The supply line has come under attack on both sides of the border this year, raising fears that the Taleban are mimicking tactics used against the British in 1841 and Soviet forces two decades ago.

Last Monday about 60 militants hijacked a convoy of supplies, including Humvees and food from the World Food Programme, near the entrance to the Khyber Pass. In August, suspected militants in Karachi set light to two Nato armoured vehicles. In April, four US helicopter engines worth £7 million went missing on the way from Kabul to Pakistan, while in March militants destroyed 36 fuel tankers in Landikotal, a border town in northwestern Pakistan.

The WFP said that it had lost $520,000 (£346,000) of food in attacks in Afghanistan and another $320,000 in north-western Pakistan this year."It's got really dangerous," the head of one Pakistani freight company said. "Chaman is still the worst, but Khyber's getting worse by the day and winter's approaching, so we need to get the supplies in before the snow comes."

Some Western officials fear that such attacks could increase if Asif Ali Zardari, Pakistan's new President, fails to defeat the militants on the Afghan border. Escorts for the convoys will place added strain on the Pakistani Army and the paramilitary Frontier Corps, which are involved in operations in the Bajaur tribal region and nearby Swat Valley.

Nato and US officials say that the attacks have not affected their operations in Afghanistan and refuse to give details of which supply routes they use, for security reasons. "We have multiple supply routes and we can adjust our flow at any time," a coalition official said.

Nato struck a deal with Moscow to open a new supply route through Russia and Central Asia, but it has yet to be approved. The alliance is also wary of giving Moscow a stranglehold on its supplies in Afghanistan after their dispute over the war between Russia and Georgia.