He had been savagely decapitated and had his head placed on his back

Jihadis loyal to the Islamic State in Egypt claim to have brutally beheaded the Croatian hostage who was seen begging for his life in a chilling video message released last week.

Depraved ISIS supporters took to social media to share a photograph purporting to show the body of 30-year-old Tomislav Salopek, who has been held by militants in Sinai province since July 22 after being kidnapped in the capital Cairo.

The gruesome image appears to show Mr Salopek's severed head placed on his back - a trademark of ISIS militants who have brutally beheaded at least seven Western hostages over the past year.

Buried in the sand next to his bloodied corpse is the chilling black and white flag used by ISIS.

The 30-year-old oil and gas sector surveyor is the first foreign captive to be killed in this way in Egypt since the extremists set up a branch in the country

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Depraved: ISIS supporters took to social media to share a photograph purporting to show the body of 30-year-old Tomislav Salopek, who has been held by militants in Sinai province since July 22

Tomislav Salopek was brutally killed by an Egyptian group calling itself the Sinai Province of the Islamic State

So far ISIS has not released video footage of Mr Salopek's beheading, although ISIS sympathisers are speculating that one will appear online shortly.

The Foreign Secretary has condemned the apparent murder of a Croatian hostage held by so-called Islamic State's Egyptian affiliate.

His death follows the IS killings of foreign journalists and aid workers in Syria, including Britons David Haines and Alan Henning.

Philip Hammond insisted Britain would stand by Croatia and Egypt as they oppose 'this inhuman brand of terrorism' after the image of Mr Salopek emerged.

Mr Hammond said: 'If these reports are true, I condemn in the strongest terms the apparent brutal killing of Croatian national Tomislav Salopek by Isil in Egypt.

'My thoughts and condolences are with his family, colleagues and all the Croatian people.

'Britain will stand by Egypt and Croatia as we continue to oppose this inhuman brand of terrorism.'

Last week a video was shared ISIS sympathisers, showing Mr Salopek wearing a yellow jumpsuit and kneeling before a knife-wielding masked man wearing military fatigues.

Reading from a note, the captive identifies himself as a Croatian national and says ISIS fighters captured him on July 22.

Hostage: Last week a video was shared ISIS sympathisers, showing Mr Salopek wearing a yellow jumpsuit and kneeling before a knife-wielding masked man wearing military fatigues

'My name is Tomislav Salopek, I am 30 years old and I am coming from Croatia... I am married and I have two children,' he said.

Mr Salopek was kidnapped while heading to work in a company car which belongs to French firm Compagnie Generale de Geophysique, who he worked for as a topographer.

Mr Salopek, 31, continues: 'They want to substitute me with the Muslim womens arrested in Egyptian prisons... This matter have to be achieved before 48 hours from now, if not the soldiers of Wilyat Sina will kill me.'

The father-of-two was married to a woman named Natasa, who is from the Croatian capital Zagreb.

His family was with him in Cairo, but they have moved back to Croatia since he was captured. Salopek was due to return with them - to their home in the eastern Croatian town of Vrpolje - just two days after he was abducted.

Croatian media has speculated that the extremists who captured him may have mistaken him for a French citizen.

Wilyat Sina is the Arabic phrase for the Egyptian group calling itself the Sinai Province of the Islamic State.

It was not clear where the video, entitled 'A Message to the Egyptian Government', was shot. Nor was it exactly clear who the militants wanted released.

Egypt, a majority Muslim country, now holds thousands of Islamists and suspected supporters of the outlawed Muslim Brotherhood group in prison.