Israeli air strikes on military posts south of Damascus killed five foreign fighters and wounded others, a Syrian war monitor said.
Lebanese militant group Hezbollah said one of its fighters, Ali Mohsen, was killed in the Monday night strike near Damascus International Airport, south of the Syrian capital.
The Syrian Observatory for Human Rights said from Britain that it was not immediately clear whether those killed were Iranians or members of Iran-backed groups.
The observatory said the wounded included four foreign fighters and seven Syrian members of an air-defence unit.
It said the air strikes hit arms depots and military posts on the southern edge of Damascus.
On Monday, the Syrian military said the country's air defences responded to Israeli air raids in southern Damascus and that the attack wounded seven soldiers and caused damage.
Syrian state media quoted a military official as saying that Israeli warplanes carried out the attack while flying over the occupied Golan Heights.
Israel seized the territory from Syria in the 1967 Arab-Israeli war.
The official said several missiles were shot down before they reached their target.
Israel rarely comments on such reports but is believed to have carried out scores of raids to disrupt Iran's military presence in Syria.
In the past two months, Syria accused Israel of carrying out at least eight air raids on its territory. The last reported strikes came in late June.
Iran has been an important ally of the Syrian government during the civil war. Tehran sent thousands of fighters into battle alongside Syrian government forces.
Israel regards Iran as a regional menace and has promised to prevent any permanent Iranian military build-up in Syria, particularly near its border.
