Pakistan on Tuesday signed a deal with the United States allowing NATO convoys to travel into Afghanistan until the end of 2015, seeking to draw a line under a seven-month border blockade.

Islamabad agreed to reopen land routes for NATO goods on July 3 after the longest suspension of the 10-year war in Afghanistan in protest at botched US air raids that killed 24 Pakistani troops, but few trucks have made it across since then.

The agreement is part of efforts by the allies to patch up their fractious relationship, which plunged into crisis last year over the US raid that killed Osama bin Laden, who was hiding in Pakistan, and the air strikes.

It comes just a day before the head of Pakistani intelligence, Lieutenant General Zaheer ul-Islam, begins a three-day visit to Washington for talks with the head of the CIA, which has been interpreted as another sign of a gradual rapprochement.

Under the deal signed in Rawalpindi, the home of Pakistan's powerful military, the United States will release $1.1 billion under the Coalition Support Fund to reimburse the troubled nation for fighting militants within its borders.

A US official said the deal lasts until the end of 2015, well beyond the 2014 departure date for the bulk of NATO's 130,000 combat troops from Afghanistan, and can be renewed for one-year intervals beyond that.

The deal specifies routes to be taken and has a list running to several pages of lethal supplies that may not be transported through Pakistan, although armoured vehicles and Humvees are permitted provided they are not mounted with weapons.

Guidelines laid out by the Pakistani parliament earlier this year insisted that no weapons and ammunition be transported through the country, though Western officials say this never happened in the first place.

A Pakistani official said the deal gave Islamabad the right to refuse or reject any shipment and special radio chips would be fitted to containers for monitoring.

Richard Hoagland, the deputy US ambassador to Islamabad who signed the agreement on behalf of Washington, hailed it as a "demonstration of increased transparency and openness" between the two governments.

Pakistan lifted its blockade after US Secretary of State Hillary Clinton said sorry for the air raid deaths, but rows over security guarantees and compensation have delayed a resumption of normal traffic.

Officials closed the Torkham border crossing, the quickest route to Kabul from the port city of Karachi, to NATO traffic on Thursday over security fears.

The Pakistani Taliban have vowed to attack NATO supplies and last Tuesday, one of the truck drivers was shot dead in the northwestern town of Jamrud.

Asif Yasin Malik, the top civil servant at the Pakistani defence ministry who attended the ceremony, said the deal would contribute to the stability of the region and hailed it as a "landmark event".

In Karachi, a leading subcontractor in the business, Alhaj Taj Mohammad, said Tuesday's agreement could help resolve the rows over security and compensation but predicted it could still take 10 days to start clearing goods from customs.

But Akram Khan Durrani, chairman of the All Pakistan Oil Tankers Owners Association, said fears about security would remain. "No owner is going to move his vehicle until solid guarantees are given for it," he told AFP.

The US official confirmed that security for convoys was not part of the MoU, saying that was Pakistan's responsibility.