The Syrian army, backed by Hezbollah fighters, closed in on the city of Zabadani near the border with Lebanon on Friday, a Lebanese security source said, and Syrian media said at least 20 insurgents had been killed in the battles to seize high ground. Violence from Syria's four-year war has regularly tipped over into Lebanon, and militiamen from the Iranian-backed Lebanese Shi'ite Muslim group Hezbollah have been fighting on the side of Syrian President Bashar al-Assad. Syrian state news agency SANA, citing a Syrian military source, said the army had gained control of at least ten 'strategic areas' to the west of Zabadani. The military had 'managed to kill and injure a large number of terrorists' and destroyed many of their bases, it said.