Hundreds of lorries carrying supplies for Nato were trapped in Pakistan by the closure [File: AFP]

Pakistan has reopened a key border crossing used by Nato forces to supply troops in Afghanistan, officials have said.

The Torkham crossing was operating again on Sunday, 11 days after it was closed amid Pakistani anger over a cross-border US helicopter raid that killed two Pakistani soldiers in the country's northwest.

"The first convoy of more than a dozen vehicles left for Afghanistan this afternoon," Mohammad Nawaz, a customs official, told the AFP news agency.

He said that more vehicles loaded with supplies for Nato and US troops were ready to set off in the coming hours.

"I am very happy that our difficult days have finally ended and we are through now," Khan Rehman, a driver, told The Associated Press news agency before driving the first lorry into Afghanistan shortly after noon.

"I am thankful to the government of Pakistan for ending our hardship."

Lorries stranded

Hundreds of lorries had been left stranded on roads across the country while Torkham was closed, while armed groups had taken advantage of the situation, setting about 100 vehicles carrying Nato supplies on fire.

Lorry routes through Pakistan bring in around 40 per cent of supplies for Nato forces in Afghanistan, according to the US Transportation Command.

Of the remainder, another 40 per cent comes through Afghanistan's neighbours in the north and 20 per cent by air.

The Pakistani government announced that the crossing would be reopened "with immediate effect" in a statement on Saturday.

"After assessing the security situation in all its aspects, the government has decided to reopen the Nato/Isaf supply from the Pakistan-Afghanistan border at Torkham with immediate effect," it said.

Richard Snelsire, the US embassy spokesman, said the US welcomed the reopening of the border crossing, and called it "a positive development".

Nato and the US apologised on Wednesday for the deaths of the Pakistani soldiers in the cross-border attack.

Drone attacks

Pakistan's relations with Nato were strained before the incident due to the intensifying drone attacks in the northwestern tribal regions.

Security officials in Pakistan said seven people were killed in the latest such attack on a compound in North Waziristan on Sunday.

Pakistan has said that there was "no justification nor understanding" for US drone strikes on its soil, which have killed about 150 people in the past month.

"We believe that they are counter-productive and also a violation of our sovereignty," Abdul Basit, a foreign ministry spokesman, said. "We hope that the US will revisit its policy."