BEIRUT: Syrian troops backed by Lebanese Hezbollah fighters swept south of the capital Damascus Wednesday, seizing strategic hills and villages from Free Syrian Army rebels and Nusra Front militants near the Israeli-occupied Golan Heights.

State media and opposition activists said the offensive was aimed at forcing back rebels who had recently advanced closer to embattled President Bashar Assad’s seat of power.

The region is located near the Israeli-occupied Golan Heights, which on Jan. 18 was targeted by an Israeli airstrike that killed six Hezbollah fighters and an Iranian general.

The Syrian government last year lost large parts of Qunaitra province to opposition fighters, many of them from the Nusra Front.

State television said troops Wednesday gained control of the town of Deir al-Adas and the village of Deir Maker, as well as the nearby areas of Tal al-Arous and Tal al-Sarjeh south of the capital.

A statement by the Syrian armed forces said the gains were important because they severed supply lines and communication among “terrorist outposts” in the Damascus countryside, Deraa province and Qunaitra.

Activists said the operation was being led by Hezbollah’s special forces. Rami Abdel-Rahman, who heads the Britain-based Syrian Observatory for Human Rights, said their aim appears to be to set up a border zone under Hezbollah’s control next to the part of the Golan seized by Israel in 1967.

The Observatory, which relies on a network of activists around the country, said Iranian volunteers are also taking part in the fighting. It said 20 opposition fighters were killed there Tuesday alone. The report could not be independently confirmed.Other sources, however, from both sides said the offensive aimed to shield Damascus, a short drive to the north, after insurgents had made significant gains in the south in recent months, taking several military bases.

“The regime wants to lay down a defense line around Damascus,” said the rebel, Abu Ghayath, spokesman for the Saif al-Sham Brigades, part of the “Southern Front” rebel alliance. Speaking via the Internet from inside Syria, he said his group had a battalion deployed in the battle.

Southern Front spokesman Issam Rayyes said government forces suffered heavy losses but they appeared determined to continue the advance, while acknowledging the loss of territory. “The shelling is extremely heavy, their losses are major but they are not stopping. For us in this case the policy of holding ground is not a successful one.”

Syrian state TV broadcast live from Deir al-Adas, some 30 kilometers south of Damascus that it said had been captured. The sound of artillery fire could be heard.

“We were able to liberate this town, and, God willing, the rest of the towns will be liberated,” said a Syrian military officer interviewed on state TV from Deir al-Adas.

Media close to the Syrian government and Hezbollah said the operation had been several weeks in the planning.

“This is the biggest offensive so far,” said Assad Zoubi, a defected Syrian army colonel based in Amman, Jordan, and is affiliated with the Southern Front groups. “Their aim is to move toward and recapture the strategic Tal Hara area, which the rebels took nearly six months ago,” he said.