Israeli strikes hit arms depot near Damascus airport
The explosion was heard across the capital, jolting residents awake, the head of the Syrian Observatory for Human Rights Rami Abdurrahman said.
Footage purporting to show the attack was circulated online by rebel-affiliated Ghouta Media Centre. Casualties had not been confirmed.
Israel's intelligence minister Yisrael Katz said a massive explosion near Damascus International Airport was "consistent" with Israel's policy - but stopped short of confirming his country was behind the strikes.
"We are acting to prevent the transfer of sophisticated weapons from Syria to Hizballah in Lebanon by Iran," Katz told army radio.
"When we receive serious information about the intention to transfer weapons to Hizballah, we will act. This incident is totally consistent with this policy."
Israel carries out airstrikes in Syria to stop what it says are deliveries of advanced weapons to Hizballah group, which is fighting alongside the Syrian regime in the country’s six-year civil war.
Last month, in the most serious incident between the two countries since the conflict began, Israeli warplanes struck several targets, drawing retaliatory missile fire.
Israel used its Arrow interceptor to destroy what was believed to have been a Russian-made SA-5 missile, and Defence Minister Avigdor Lieberman threatened to destroy Syria's air defence systems "without the slightest hesitation" if it happened again.
Israel fought a devastating war against Lebanese Shia movement Hezbollah in 2006.