BEIRUT — Syrian rebels on Saturday seized a major air defense base in a strategic region in the south near the Jordanian border, the latest battlefield triumph for fighters seeking to topple President Bashar Assad, activists said.

Fighters with a rebel group active in the south stormed and seized control of the base used by the 38th Division after a 16-day siege, according to a statement posted on websites of the group known as the Yarmouk Martyrs Brigade. The base near the village of Saida is situated along the international highway linking the Syrian capital, Damascus, with Jordan to the south.

Fighting in Syria's southern provinces bordering Jordan and Israel has increased sharply in the past few days. The Syrian Observatory for Human Rights said dozens of people, mostly opposition fighters, were killed in heavy clashes this week in the Quneitra region along the cease-fire line between Syria and Israel in the Golan Heights.