Syrian army forces backed by Iranian-backed militias pushed deeper into the last rebel-held enclave near a strategic border area with Israel and Lebanon in a new expansion of Tehran's influence in the war-torn country.

The army and the Shiite forces helped by Druze militias in the area advanced east and south of the Sunni-rebel held bastion of Beit Jin backed by some of the heaviest aerial bombing and artillery shelling since a major assault began more than two months ago to seize the area, rebels said.

The Syrian army said it had encircled the village of Mughr al Meer at the foothills of Mount Hermon as troops moved toward Beit Jin amid fierce clashes. On Monday, the army said they had cut off insurgent supply lines and made further advances.