Pakistan has reopened the main supply route for US and Nato troops in Afghanistan after blocking it for three days during an operation against al-Qaeda and Taliban fighters blamed for repeated attacks on convoys in the Khyber Pass, an official said.

Authorities say the operation was a success, but a similar offensive in June failed to curtail attacks and was followed by a controversial peace deal with tribal elders in the northwest Khyber region that US officials say allowed fighters to regroup.

Tariq Hayat Khan, the top administration official in Khyber, said that the Pakistani operation would continue, but would not be close enough to the road through the Khyber Pass to disrupt traffic, allowing the supply route to reopen.

Khan displayed a large cache of weapons seized during the operation and said 43 suspected fighters had been arrested.

Securing routes

The US plans to deploy up to 30,000 additional troops to landlocked Afghanistan this year, further increasing the importance of secure supply routes through Pakistan, which deliver up to 75 per cent of the fuel, food and other goods used by Western forces.

The fighters have stepped up attacks against convoys passing through Khyber in recent months and have also ransacked terminals in the nearby city of Peshawar holding supplies intended for the Afghan army.

American officials say the attacks have not affected their ability to operate in Afghanistan, but have acknowledged they are looking for ways to improve security along the route and are investigating alternative ways to deliver supplies.

They have praised the Pakistani operation, which started Tuesday and used artillery and helicopter gunships to destroy suspected fighter hide-outs.

The US has also attempted to disrupt al-Qaeda and Taliban fighters on the Afghan border by firing missiles from unmanned aircraft.

A suspected US missile strike killed four fighters and wounded two others in the South Waziristan tribal area on Friday, the second in as many days in the lawless region.

Villager Yar Mohammed said the missile hit an abandoned school in the village of Medan.

The strikes have angered local residents and the Pakistani government, which says they are a violation of the country's sovereignty.

But the US has continued the air strikes in an attempt to stop the fighters from staging cross-border attacks against Western forces in Afghanistan.