The head of al-Qaeda’s operations in Pakistan and a leading aide have been killed, US officials and Pakistani security sources said on Friday, in what appeared to be a significant setback for the terrorist group.

Usama al Kini, widely believed to be the main planner of the truck bombing at Islamabad’s Marriott hotel last September, and Sheikh Ahmed Salim Swedan, both Kenyans, were killed by a missile from a US drone, according to a western diplomat, but US officials would not confirm any details.