Militants in southern Pakistan attacked a NATO convoy of vehicles carrying fuel for foreign troops in Afghanistan on Friday.

The attackers fired rockets at the 27 oil tankers that were parked at an ordinary fueling station in the province of Sindh. The tankers exploded and caught fire, most of them were destroyed.

About 10 gunmen attacked the vehicles after midnight. The drivers were forced to flee before the fires were set. Officials said no one was killed or wounded during the attack.

Friday's attack and the decision to close to the border have underscored the uneasy relations.

The attack comes a day after Pakistani authorities shut down a vital border crossing into Afghanistan, possibly in retaliation for a U.S. - led air strike Thursday which killed three Pakistani soldiers.

Islamic militants occassionally attack NATO supply tankers in Pakistan, mostly in the northwest where their influence is stronger.

Attacks on NATO and U.S. supply convoys in Pakistan give militants a propaganda victory, but coalition officials say they do not affect operations in Afghanistan. The vast majority travel through the country unharmed.