Israel has launched hundreds of strikes in Syria since the start of the war in 2011, targeting government troops, allied Iranian forces and Hezbollah fighters.

"Syrian air defences intercept an Israeli aggression on a research centre in Aleppo province," the official SANA news agency said.

Citing a military source, SANA later said the intercepted missiles targeted several "military depots" in the Al-Safira area southeast of Aleppo city.

The Israeli army did not comment on the reports.

The raids caused "violent explosions" in the area, according to the Britain-based Syrian Observatory for Human Rights, a war monitor that relies on a network of sources inside Syria.

The Observatory said strikes targeted weapons depots belonging to pro-Iran militias and Syrian government forces.

There were no immediate reports of casualties.

Minutes later, warplanes hit positions of pro-Iran militias in the Mayadeen desert in eastern Syria, according to the Observatory.

It was not immediately clear who was responsible but the Observatory said it was "likely" to be Israel.

If confirmed, the strikes would mark the fifth Israeli attack on Syria in two weeks.

Israel rarely confirms details of its operations in Syria but says Iran's presence in support of President Bashar al-Assad is a threat and that it will continue its strikes.

On Friday, Israeli forces hit a Hezbollah missile depot in central Syria hours after Israeli helicopters fired missiles at sites in southern Syria.