Deadly clashes raged on the edge of Damascus on Wednesday and rival rebel factions battled each other in northern Syria as international chemical weapons inspectors began to secure the sites will they will work.

The fighting underscored the immense security challenge that the dozens of disarmament experts must negotiate as they work amid the civil war to meet tight deadlines for eliminating President Bashar Assad's estimated 1,000-ton arsenal of chemical weapons.

The inspectors' mission — endorsed by a U.N. Security Council resolution passed last week — is to scrap Syria's capacity to manufacture chemical weapons by Nov. 1 and destroy its entire stockpile by mid-2014.