Israeli attack on Iranian base in Syria
The base was in the Jabal Azzan region south of Aleppo, a Syrian government-controlled rural region.
People claimed to have seen explosions at the site and there are unconfirmed reports of casualties.
Syrian media reported it was attacked by Israeli aircraft this evening.
The Syrian Observatory for Human Rights, a Britain-based war monitor, reported the blast but said the cause was unknown.
Media linked to Hezbollah later claimed there had been no airstrike, blaming explosives detonating in a warehouse.
Last week, Russia blamed Israel for an attack on a Syrian airbase that killed at least 12 people.
Moscow claimed morning that two Israeli fighter jets had launched the attack on the T4 base.
The Russian Defence Ministry said the F-15 planes had carried out the strikes from Lebanese air space.
And it claimed Syrian air defence systems had shot down five of eight missiles fired.
The Israeli military made no comment on the claims.
It comes after forces from the US, UK and France launched a series of strikes against alleged chemical weapons facilities in the country overnight.
The western powers said on Saturday their missile attacks struck at the heart of Syria's chemical weapons programme.
The United States, France and Britain launched 105 missiles overnight in retaliation for a suspected poison gas attack in Syria a week ago, targeting what the Pentagon said were three chemical weapons facilities including a research and development in Damascus' Barzeh district and two installations near Homs.
The bombing was the biggest intervention by Western countries against Assad and his superpower ally Russia, but the three countries said the strikes were limited to Syria's chemical weapons capabilities and not aimed at toppling Assad or intervening in the civil war.