ISLAMABAD: Suspected US spy drones fired missiles on Sunday into a militant training camp in a stronghold of Pakistan’s top Taliban commander, killing at least 20 people, security officials said.

The air strike in the restive South Waziristan tribal zone bordering Afghanistan was the latest in a string of attacks on Pakistani soil that have raised tensions between Islamabad and Washington.

It targeted a compound near the town of Ladha, one of the main sectors held by Taliban leader Baitullah Mehsud, who has been accused of masterminding the assassination of former Pakistani premier Benazir Bhutto in December. There were no immediate indications that Mehsud, the chief of Tehreek-e-Taliban Pakistan (Pakistan Taliban movement), was targeted in the attack.