PESHAWAR: Pakistani truck drivers carrying supplies to Nato troops in Afghanistan say they are worried about militant attacks after their country closed its border crossings in retaliation for coalition airstrikes that allegedly killed 24 Pakistani troops.

Nearly 300 trucks were stranded at Pakistan's two Afghan border crossings Sunday, a day after the alleged Nato attack and Islamabad's quick decision to block the coalition's supplies.

"We are worried," said driver Saeed Khan. He spoke by telephone from the border terminal in Torkham. "This area is always vulnerable to attacks. Sometimes rockets are lobbed at us. Sometimes we are targeted by bombs."

Khan and hundreds of other drivers and their assistants barely slept Saturday night because they were worried about potential attacks, he said.

Some drivers said Pakistan had sent paramilitary troops to protect their convoys since the closures, but others were left without any additional protection.Even those who did receive troops did not feel safe.

"If there is an attack, what can five or six troops do? Nothing," said Niamatullah Khan, a fuel truck driver who was parked with 35 other vehicles at a restaurant about 125 miles from Chaman. "It is just a matter of some bullets or a bomb, and that's it."

Nato ships nearly 50 per cent of its non-lethal supplies to its troops in Afghanistan through Pakistan. The trucks are periodically targeted by suspected militants as they travel through the country, and their occupants are sometimes killed.

Nato has said these attacks do not significantly impact its ability to keep its troops supplied.

A prolonged closure of the border would, however. Nato has reduced the amount of supplies it ships through Pakistan from a high of around 80 per cent of its total non-lethal supplies by using routes through Central Asia, but they are costly and less efficient. It would likely be difficult to increase significantly the amount of supplies shipped on these alternative routes in a short timeframe if Pakistan's borders remain closed.

Some critical supplies, including ammunition, are airlifted directly to Afghan air bases.