ISIS terrorists have shot down a fighter jet over Syria and posted barbaric images of his corpse crucified below a model of a plane.

The jet, believed to belong to the Syrian air force, was shot down near the eastern city of Deir ez-Zor earlier today as it carried out air strikes against ISIS insurgents.

The Amaq agency, which is closely aligned with ISIS, released video footage showing the flaming wreckage of a plane scattered across a stretch of barren rocky ground.

The pilot's body was taken from the cockpit and hung in the street in a mock crucifixion, with a model aeroplane above his head

It then showed a corpse in military uniform and white helmet, hung out for display on a street.

The Syrian Observatory for Human Rights, which monitors Syria's war through a network of sources inside the country, said ISIS had shot down the plane in the Thardah hills, about three miles from Deir ez-Zor air base.

ISIS controls most of the eastern province of Deir ez-Zor, but forces loyal to President Bashar al-Assad hold the air base part of the city itself.

It comes as Assad accused the United States of not being serious about defeating ISIS.

The wreckage of the plane was shown in the ISIS video. It is not known how ISIS shot down the jet

It was not clear whether the jet was brought down by a missile or with gunfire but it is the second jet to be brought down over ISIS territory since April.

ISIS, sometimes referred to as Daesh, have also shot down two helicopters in recent months.

Last week footage emerged of a Russian helicopter being shot down near Palmyra.

Meanwhile the Syrian Observatory for Human Rights said at least 12 civilians were killed by air strikes in rebel-held neighbourhoods in the city of Aleppo.

Nine people were killed in the Tariq al-Bab district and three died in Salhin, both in eastern Aleppo.

The plane was shot down in an area which is largely controlled by ISIS

It is not clear if the planes which bombed the areas were Syrian or Russian.

Moscow is a close ally of Assad and the Russian air force has been heavily involved since September in the fighting against both ISIS and moderate rebel groups such as the Free Syrian Army.

Mohamed Qattan dug through the debris with his bare hands and said: 'My family are beneath the rubble. I was praying at the mosque when the strike happened.

'My wife and two of my children - my son and daughter - are underneath the rubble,' he told AFP.

Bashar al-Assad (left) is greeted by Russian President Vladimir Putin during a visit to Moscow. Putin has backed Assad to the hilt with military hardware and firepower

Aleppo city is divided roughly between government control in the west and rebel control in the east.

Last week government forces advanced to within firing range of the only remaining supply route into the rebel-held east, effectively cutting it off and prompting food shortages and spiralling prices.