TRIPOLI, Libya — Libyan rebels staged an armed uprising against Moammar Gaddafi in the western city of Zlitan on Friday, a rebel spokesman said, adding that 22 of their fighters had been killed. The clashes, if confirmed, would mark the first significant rebel attempt to take control of a major city in western Libya since the early days of the uprising. Zlitan lies just over 100 miles east of Tripoli and about 30 miles west of the besieged rebel-held city of Misurata.