Sheikh Muftah al-Fitouri, who preached at the city's Benina air base, was killed when an explosive device attached underneath his car detonated today, the official said.
In Benghazi's Al-Lithi area, gunmen also shot dead Omar al-Orfi, who served in now slain dictator Muammar Gaddafi's internal security agency, the source added.
A spate of attacks on security personnel and other officials who served under Gaddafi has rocked Benghazi since his overthrow in 2011.