Israel said it had downed a Syrian warplane over the Golan Heights on Tuesday, the first incident of its kind in more than three decades and a sign of the growing risk to regional stability as the Syrian conflict drags in its neighbours.

The Israeli military said that the Syrian Sukhoi fighter jet was shot down by its US-made Patriot missile system after it "infiltrated Israeli airspace" over the area, a disputed territory captured from Syria by Israel during the 1967 Six Day War.

Video footage posted on YouTube showed what appeared to be the burning wreckage of the plane falling from the sky. Two parachutes are also seen as the crew ejected from the jet.

The plane may have accidentally strayed into Israeli airspace while attacking rebel targets on the Syrian side of the border, according to early indications.

The Syrian Observatory for Human Rights, a UK-based monitoring group, said the fighter jet had been bombing areas outside the border town of Quneitra.

Israeli Defense Minister Moshe Yaalon said the plane "approached Israeli territory in the Golan Heights in a threatening manner, and even crossed the border." But his statement also alluded to the possibility the incursion was accidental.

Yaalon said Israel "will not allow any element - neither a state nor a terrorist group - to threaten our security and violate our sovereignty", adding that the Israeli response to such threats would be robust "whether they stemmed from a mistake or were deliberate".

Syria condemned the downing of the plane as an "act of aggression" in a statement on state television, and linked it to the US-led airstrikes on Islamic State targets in the country overnight.

While the incident coincided with the launch of foreign airstrikes, it does not appear to have been directly related. However the downing of the Syrian plane - the first at Israel's hands since the 1982 Lebanon war - does indicate the growing challenges for Jerusalem as it attempts to stay out of the conflict next door.