BEIRUT — Syrian rebels launched a wide-ranging offensive against government positions near the Israeli-occupied Golan Heights on Wednesday, after shelling in and around Damascus killed at least 33 people, activists said.

The rebels of the Southern Front alliance and the so-called Haramoun Army targeted several areas in the Golan, including the towns and villages of Quneitra, Khan Arnabeh, Baath, Jiba and the base of Brigade 90, the main government force in the region, said opposition activist Jamal al-Jolani, who is based in southern Syria.

“The fighting now is inside the city of Quneitra,” al-Jolani said via Skype. He said the Haramoun Army — which includes al-Qaida’s Syrian affiliate and the ultraconservative Ahrar al-Sham — shelled the area while Southern Front fighters advanced on the ground.

Insurgents have been on the offensive in southern Syria for the past three months, capturing military bases, villages and a border crossing point with Jordan.

Maj. Issam el Rayyes, a spokesman for the Southern Front, said the aim of the offensive “is to liberate remaining regime targets in Quneitra.” He added that they aim to link southern Syria with rebel-held neighborhoods in the suburbs of Assad’s seat of power in the capital, Damascus.

“This is a wide battle, not a simple one,” he said, adding that in addition to the towns and village in Quneitra, the rebels are fighting to control a series of strategic hills in the southern region.