At least 23 people were killed in Syria in a Thursday pre-dawn raid, attributed to Israel, said a war monitoring group. Three of the victims are reported to be Iranian nationals.
The Syrian Observatory for Human Rights said at least 15 of those killed belonged to pro-Iranian militias operating in the country and eight of the victims were part of the official Syrian army.
Earlier reports placed the number of fatalities at only 12.
A few hours before the attack, an Iranian cargo plane operated by Tehran-based Saha Airlines - owned by the Islamic Revolutionary Guard - was spotted making its way back from Damascus to the Iranian capital.
The aircraft flying along the route that in the past was used to transport arms from Iran to Syria.
The state news agency SANA said the Syrian air defenses shot down most of the missiles in the suburbs of the capital and the country's south before they reached their targets. It said the Israeli warplanes fired the missiles while flying over the Israeli-occupied Golan Heights and neighboring Lebanon.
The Britain-based Syrian Observatory for Human Rights, which tracks the Syrian war through a network of activists on the ground, said the airstrikes that occurred after midnight on Wednesday. They hit Syrian army positions and those of Iranian-backed militiamen west and south of the capital, as well as the Mazzeh military airbase in Damascus. the Observatory said.
A "large number of missiles" hit multiple positions in these areas, triggering a fire at the Scientific Research Center in the Damascus suburb of Jamraya. The Observatory said the strikes inflicted casualties but had no definitive figure.
There was no immediate comment from Israel.