Mahan Air airplane
Mahan Air airplaneiStock

The Syrian ambassador to Tehran said on Saturday that the "harassment" against an Iranian passenger plane over Syrian skies by the United States was a "terrorist act," Xinhua reported.

"Harassment against the Iranian passenger plane of Mahan airline by the US fighter jets in Syria's sky is a symbol of the US terrorist actions against civilians," the ambassador, Adnan Hassan Mahmoud, said in a statement.

Mahmoud said that "it is a violation of law and international agreements on non-military flights."

The ambassador also noted that the presence of “occupying forces” in Syria threatens "security and stability in the region."

Iran had said that one of its airliners, flying from Tehran to Beirut on Thursday, was "harassed" by fighter jets, but later landed safely in Lebanon. The incident was originally blamed on Israel but Iran later confirmed the fighter jet was an American jet.

A US official confirmed a US jet had passed by the Iranian airliner, but at a safe distance.

Iran's foreign minister, Mohammad Javad Zarif, said on Friday that the incident was an act of "lawlessness upon lawlessness."

"US illegally occupies territory of another State and then harasses a scheduled civil airliner—endangering innocent civilian passengers—ostensibly to protect its occupation forces," he wrote.

Tensions between the US and Iran have escalated since the US withdrawal from the Iran nuclear agreement. In addition, the US and Iran have had several close encounters in the Persian Gulf.

The US Navy recently issued a warning to mariners in the Gulf to stay 100 meters away from US warships or risk being “interpreted as a threat and subject to lawful defensive measures”.

While no mention was made of Iran in the notice, it followed President Donald Trump’s threat to fire on any Iranian ships that harass Navy vessels.

Trump’s warning came after a tense encounter between US and Iranian ships in the Persian Gulf.

The US military said at the time that 11 Revolutionary Guards naval vessels from the Guards navy came close to US Navy and coast guard ships in the Gulf, calling the moves “dangerous and provocative”.

Iran’s Revolutionary Guard acknowledged that the incident had taken place, but also claimed that it was American forces who sparked the incident.