Israeli intelligence officials are trying to verify reports that Iraqi pilots have joined the ranks of the Islamic State terrorist organisation in Syria, and are currently operating at least three jet fighters taken from a Syrian air base.

According to the as-yet unconfirmed reports, members of the Islamic State have flown three Mikoyan MiG-21 or MiG-23 combat aircraft over a zone that the militant group controls. The aircraft were seen flying over a captured Syrian military airport in the northern Aleppo province, the reports claim.

The initial reports are in line with prior indications that the Islamic State is trying to gain some air capability in the fighting in Syria and Iraq.

Israel’s air force has been on its highest level of alert in northern Israel because of the unstable situation in Syria.

A Syrian air force Sukhoi Su-24 was shot down on 23 September by an Israeli Raytheon Patriot surface-to-air missile, after the aircraft approached the Israeli border on the Golan heights.