From Idris Ali and Phil Stewart

WASHINGTON, March 3 (Reuters) - U.S. Marines fired on protesters during the weekend raid on the consulate in Karachi, two U.S. officials said on Monday, in a rare use of force at a diplomatic mission that could sharply escalate tensions in the country amid mass protests over the assassination of Iranian Supreme Leader Ali Khamenei.

Ten people were killed on Sunday when protesters breached the outer wall of the consulate following the killing of Khamenei in airstrikes on Iran.

Based on preliminary information, the two U.S. officials said it was not yet clear whether any Marines had shot or killed anyone. They also did not know whether other parties protecting the mission, including private security guards and local police, had fired shots.