This is the second time in less than seven months that the Damascus airport, where Iranian-backed armed groups and Lebanese Hezbollah fighters are present, has been hit by Israel.

The attack -- which occurred around 2:00 am (2300 GMT) -- put the country's main airport out of service, according to Syria's state news agency SANA.

Israel carried out the strike with "barrages of missiles, targeting Damascus International Airport and its surroundings", a military source told SANA, which reported that two Syrian soldiers were killed.

But the Britain-based Syrian Observatory for Human Rights -- which relies on a wide network of sources on the ground in Syria -- said a total of four people had died in the early morning attack.

"Four fighters including two Syrian soldiers were killed" by the Israeli strike, Rami Abdul Rahman, head of the Observatory, told AFP.

The missiles also hit "positions for Hezbollah and pro-Iranian groups inside the airport and its surroundings, including a weapons warehouse", Abdul Rahman said.

Since civil war broke out in Syria in 2011, Israel has carried out hundreds of air strikes against its neighbour, targeting government troops as well as allied Iran-backed forces and fighters from Lebanon's Shiite militant group Hezbollah.

While Israel rarely comments on specific reports of its attacks, it has repeatedly said it will not allow its archfoe Iran to gain a foothold in Syria.