The Islamic State insurgent group circulated photos and a video on social media on Tuesday purporting to show captive Jordanian pilot Muath Al-Kasaesbeh being burnt alive.

The images showed a burning man standing in a cage. Kasaesbeh was apparently placed in the cage on open ground, draped in the now traditional orange robes, doused in flammable liquid, and set alight. The authenticity of the images has not been confirmed.

Jordanian state TV reported that he had been killed one month ago. A relative of Kaseasbeh told Reuters that the Jordanian armed forces had informed the family that he had been killed.

The Jordanian army said in response to the video that it would avenge Kaseasbeh's death. "The revenge will be as big as the calamity that has hit Jordan," army spokesman Colonel Mamdouh al Ameri said in a televised statement. A government spokesman promised a "strong, earth-shaking and decisive" response.

According to other media reports, Jordan intends to execute a female suicide bomber held in Jordan within hours. Jordan had previously offered to free Sajida al-Rishawi, an Iraqi who participated in the bombing of an Amman hotel in 2005, in return for the pilot's release.

Kaseasbeh, 26, a first lieutenant in Jordan's air force, was captured on Christmas Ebe after his F-16 jet crash-landed near the Syrian city of Raqqa, which is held by ISIS (also known as ISIL).

In the video, Kasaesbeh is shown, with a black bruise under his left eye, at the scene of an apparent western coalition air raid. Watched over by as many as nine uniformed ISIS militants, he is paraded at the rubble-strewn site, while the video flashes back to scenes of destruction from the time of the raid itself.

Subsequently, he is seen standing in the cage, with a cross of flammable material under his feet. A masked executioner lights a long fuse from outside the cage, flame snakes towards Kasaesbeh and he is burned alive. The full duration of the burning is captured on the video.

At the end of the video, English text offers a ransom for other downed pilots, according to the Vocativ website.

ISIS militants seen among the rubble of a building in the clip purportedly showing the execution of the captive Jordanian pilot.

“The Islamic State announces a reward of 100 Gold Dinars to whoever kills a crusader pilot. The diwan for state security has released a list containing the names of Jordanian pilots participating in the campaign. So good tidings to whoever supports his religion and achieves a kill that will liberate him from hellfire."



The video then lists several high-profile Jordanian Air Force figures, with “Wanted” beside their names.

U.S. President Barack Obama reacted to the video by saying that if indeed it is real, it is yet another indication of the group’s barbarity, and would re-double the determination of the global coalition to degrade and destroy ISIS.

Kaseasbeh was carrying out air strikes against the militants when his warplane crashed near the northern Syrian city of Raqqa, the Islamic State group's de facto capital. The group has executed captured Iraqi and Syrian Muslim soldiers in the past — it follows an extremist version of Islam that considers rivals, even some Sunni Muslims, as apostates. Still, the group may want to negotiate a prisoner swap or other concessions from Jordan.

After Al-Kaseasbeh capture, ISIS militants in Syria initiated a Twitter discussion on the best way to kill the "Jordanian pilot pig." The Arabic hashtag “Suggest a Way to Kill the Jordanian Pilot Pig” was retweeted over a thousand times. Some of the ideas shared by ISIS followers included beheading the pilot, burning him alive and running him over with a bulldozer.

Pictures of Jordanian pilot, Lt. Muath al-Kaseasbeh, displayed in his native country (AP)