A source in the Syrian opposition claimed Thursday that rebel fighters destroyed an Iranian plane carrying arms to the embattled regime of President Bashar Assad.

No confirmation of the report was available. Syria’s state run SANA news agency denied the claim and said the airport was operating as normal.

According to the unnamed source, cited by Israeli media, the aircraft attempted to land at the international airport in Damascus on Thursday with a weapons shipment for the Syrian army. The rebels said the plane was hit and caught fire, setting sections of the airport ablaze.

Iran has long been suspected of providing a weapons lifeline to Syria, mostly using flights or convoys passing through the territory or airspace of Iraq.

On Sunday, US Secretary of State John Kerry confronted Iraq for continuing to grant Iran access to its airspace.

Speaking to reporters during a previously unannounced trip to Baghdad, Kerry said that he and Iraqi Prime Minister Nouri al-Maliki had engaged in “a very spirited discussion” on the Iranian flights, which US officials believe are ferrying weapons and fighters intended for the Syrian government.

Kerry said the plane shipments — along with material being trucked across Iraqi territory from Iran to Syria — were helping President Bashar Assad’s regime cling to power by increasing their ability to strike at Syrian rebels and opposition figures demanding Assad’s ouster.

The Associated Press contributed to this report.