Syrian government forces backed by Russian airstrikes drove Islamic State fighters from Palmyra on Sunday, ending the group's reign of terror over a town whose famed 2,000-year-old ruins once drew tens of thousands of visitors each year.

Government forces had been on the offensive for nearly three weeks to try to retake the central town, known among Syrians as the "Bride of the Desert," which fell to the extremists last May. Their advance marks the latest setback suffered by IS, which has come under mounting pressure on several fronts in Iraq and Syria in recent months.

Syrian TV quoted an unnamed military official as saying that "the armed forces and groups of popular defense committees have fully taken control of Palmyra." The popular defense committees are militias allied with the government.