Pakistan is doubling the capacity for NATO trucks at a key border crossing, officials said Monday, to speed up processing for an expected influx of supplies for troops in Afghanistan.

Customs officials at Torkham border crossing in the country's troubled northwest told AFP that work had begun to expand dedicated parking space for NATO containers.

Islamabad agreed to reopen overland routes to NATO convoys last week after a seven-month blockade sparked by a botched US air raid on a border post that killed 24 Pakistani soldiers.

"After expansion the parking capacity for NATO trucks will be doubled," Obaidullah Khan, a customs official at Torkham, the closest border crossing to Kabul, told AFP.

"Prior to the closure the terminal had a parking capacity of 250 vehicles and now we are expanding it to 500."

Khan said work was also under way on two dedicated rooms for customs officers dealing with paperwork for NATO vehicles, to speed up their transit into Afghanistan.

The terminal remained quiet on Monday as no NATO supply trucks were able to reach Torkham from the Arabian Sea port of Karachi, where they have languished for the past seven months.

A bulldozer had begun work at the site, uprooting trees while workers spread barbed wire around the back of the terminal, an AFP reporter saw.

Security at the crossing is being boosted, Khan said, to foil Taliban militants who have vowed to attack NATO trucks and kill their crews.

Four checkpoints are being set up around the Torkham terminal and the number of security personnel will be raised from the previous level of 550.

"No NATO supply vehicle will be allowed to pass a night at Torkham, even if we need to work for extra time," Khan said.

An AFP reporter saw the expanded area of the terminal enclosed with barbed wire from three sides and tribal policemen standing guard.

"We are ready to receive any NATO truck here, you will see more arrangements after the trucks reach here," Meraj Khan, the administrative official at Torkham told AFP.

The land routes into Afghanistan are vital as the United States and NATO withdraw troops and equipment that has built up since the 2001 invasion.

The blockade had forced the United States and its allies to rely on longer, more expensive routes through Central Asia, Russia and the Caucasus, costing the US military about $100 million a month, according to the Pentagon.