A massive blast near Damascus International Airport early today was likely caused by an Israeli air strike said Lebanon's Al-Manar, a television channel affiliated with the Syrian government ally Hezbollah.
A spokeswoman for the Israeli military, asked if Israel had been involved in carrying out airstrikes targeting Damascus airport, said: "We can't comment on such reports."
Two senior rebel sources operating in the Damascus area cited their monitors in the eastern outskirts of the capital where the airport is located as saying that five strikes had hit an ammunition depot used by Iran-backed militias.
Read: Jordan warns Lebanon of imminent Israeli strike
Al-Manar said initial indications were that the blast had caused only material damage and no human casualties.
Syrian President Bashar Al-Assad is backed in the war by Russia, Iran and regional Shia militias including Hezbollah, which is a close ally of Tehran and a sworn enemy of Israel.
Israeli officials have cited any movement of advanced weaponry to Hezbollah units in Syria as a "red line" that has prompted it to carry out airstrikes or artillery fire in the past.
Pro-Syrian government media and the Britain-based Syrian Observatory for Human Rights early today reported a large blast near the airport and a resident of central Damascus, several kilometres away, said it woke her from sleep.
The rebel sources said the attack caused a fire with flames appearing to come from a closed military area of the sprawling complex they believed was used by Tehran to supply weapons to Iranian-backed militias operating alongside the Syrian army.