BEIRUT — Syrian rebels brought their fight within a mile of the heart of Damascus on Friday, seizing army checkpoints and cutting a key highway with a row of burning tires as they pressed their campaign for the heavily guarded capital, considered the likely endgame in the nearly 2-year-old civil war.
The clashes raised fears that Damascus, a major cultural center and one of the world's oldest continuously inhabited cities, could fall victim to a protracted battle that would bring the destruction seen in other major cities and trigger a mass refugee exodus into neighboring countries.
"Any attempt by the rebels to advance into central Damascus would mean the beginning of a very long fight," said Syrian activist Rami Jarrah. "I imagine Aleppo would be a small example of what is likely to happen in Damascus."
Aleppo, Syria's largest urban center and main commercial hub, has been convulsed by violence since the summer, when rebels launched an offensive to take control of the city. Since then the fighting has been locked in a deadly stalemate, with the war-ravaged city carved up into government- and opposition-held strongholds.
The latest Damascus offensive, launched from the northeastern side of the city, did not appear to be coordinated with rebels on other sides of the capital, and it was unclear whether the opposition fighters would be able to hold their ground.
Previous attempts to advance on the capital have failed. The government controls movement in and out with a network of checkpoints, and rebels have failed so far to make significant inroads.
In Geneva, the U.N. refugee agency reported a major increase in the number of people fleeing Syria, with 5,000 refugees crossing the borders daily into neighboring countries. The mass exodus "is really a full-on crisis," agency spokesman Adrian Edwards said.