Pakistan has temporarily stopped NATO supply trucks crossing its northwestern border into Afghanistan over security concerns due to fears of Islamist attacks, officials said Thursday.

Gunmen on Tuesday attacked a convoy of NATO supply trucks, killing a driver, in the town of Jamrud near the main northwestern city of Peshawar, in the first such attack since Pakistan lifted a seven-month blockade of the border.

"Movement of NATO vehicles has been temporarily suspended since Wednesday evening to beef up security," a paramilitary official told AFP.

"We have launched a search operation in the hills surrounding Jamrud," the official added.

On Wednesday, officials at the northwestern Torkham crossing had said traffic was picking up for the first time since the blockade ended, with more than 100 vehicles crossing in recent days.

But local administration official Bakhtiar Khan confirmed Thursday the supply route had been suspended due to "security reasons".

"Intelligence officials have informed the authority that attacks may occur on NATO vehicles this week and in the light of this a security plan is being chalked out," Khan told AFP.

He said the NATO route would "resume very soon", but that until then trucks carrying supplies for the 130,000-strong US-led mission in Afghanistan had been told not to approach the border.

"We have been told by authorities to wait here as they are building up security after the firing incident," Amanullah Khan, a NATO truck driver, told AFP in Peshawar.

So far, the closure has only affected the Torkham crossing.

At the southwestern crossing of Chaman, some 17 trucks were awaiting clearance to enter Afghanistan and 20 other trucks were parked in Quetta, clearing agent Ashraf Khan told AFP.

Islamabad closed its land routes to NATO convoys after US air strikes killed 24 Pakistani soldiers on November 26, but reopened them after Washington said sorry for the deaths.

Before the blockade, around 150 trucks crossed into Afghanistan each day at Torkham -- the closest border crossing to Kabul -- and officials say the flow will rise to up to 300 a day.

But three weeks after the blockade ended, trucks and containers are still holed up at the Arabian Sea port of Karachi, where NATO goods are unloaded for the overland route.

Workers are waiting for security guarantees and compensation for the last seven months, said Rana Mohammad Aslam, vice president of the All Pakistan Goods Carriers Association.

"Not a single truck has left town so far because of the payment issues with the subcontractors and the government's failure to devise a plan to provide adequate security to the trucks," he said.

He told AFP that Tuesday's killing had "spread more fear among truck owners and their employees".

An official at the ports and shipping ministry told AFP on the condition of anonymity that not a single container had left the port, pending customs clearance and the payment of damages.