ISIS-linked militants in Algeria have beheaded a French hostage captured at the weekend - having earlier made threats to kill him if France did not stop bombing targets in Iraq.

Herve Gourdel, 55, was captured by the Islamist group Jund al-Khilifa while hiking in the Djurdjura National Park on Sunday - just one day after he arrived in Algeria for a 10-day walking holiday.

A video featuring Mr Gourdel was released yesterday in which the militants threatened to kill the professional mountaineering guide within hours unless France stopped bombing ISIS targets in Iraq by the end of the day.

The sickening four minute 46 second video of Mr Gourdel's murder - titled 'A Message in Blood for the French Government' - was released exactly 30 minutes after Barack Obama gave a speech vowing to destroy ISIS and its affiliates to the UN General Assembly.

In his speech President Obama urged the world to come together to tackle the threat posed by ISIS and 'dismantle this network of death'. The address ended at 10.38am New York time, with the existence of Mr Gourdel's murder video revealed just 30 minutes later, at 11.09am.

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Execution: ISIS-linked militants in Algeria have beheaded French tourist Herve Gourdel after he was captured at the weekend. The group earlier made threats to kill Mr Gourdel if France did not stop bombing targets in Iraq

'Network of death': Mr Gourdel's murder came just 30 minutes after U.S. President Barack Obama gave a speech to the UN General Assembly, urging the world to unite to tackle the threat posed by ISIS and its affiliates

This afternoon the terrorism watchdog SITE Intelligence Group distributed a video by Jund al-Khilafah announcing Mr Gourdel's death.

Images of the execution emerged on social media a short time later, showing the mountaineering guide wearing a purple T-shirt surrounded by masked men, with his hands bound behind his back.

Yesterday a video posted on YouTube showed the white-haired, bespectacled Mr Gourdel surrounded by masked men holding Kalashnikov rifles.

The group threatened to kill their hostage by the end of the day unless France ceased its air strikes in Iraq, where ISIS terrorists control vast swaths of territory under the guise of a 'caliphate'.

The Algerian murderers referred to their group as Jund al-Khilifa - which means 'caliphate soldiers.'

The footage prompted some 1,500 Algerian forces to comb through the restive, mountainous Tizi Ouzou region in the east of Algeria - desperately trying to save Mr Gourdel before it was too late.

Tragic: Herve Gourdel, 55, was captured by the Islamist group Jund al-Khilifa while hiking in the Djurdjura National Park on Sunday - just one day after he arrived in Algeria for a walking holiday

Threats: A video featuring Mr Gourdel was released yesterday in which the militants threatened to kill the Frenchman unless France stops bombing ISIS targets in Iraq

Mr Gourdel's elderly parents spoke publicly about their 'horrific ordeal' shortly before he was killed.

His mother, who is in her 80s and living in Nice, said that the passionate photographer arrived in Algeria last Saturday and was about to take part 10 days of walking.

Mrs Gourdel, who did not give her first name, said: 'Everything was fine, he said he had began a two-day hike and that it might be a difficult one.'

MERCILESS: WHAT HAPPENS IN THE VIDEO OF THE BEHEADING OF HERVE GOURDEL RELEASED BY ISIS-LINKED MILITANTS The video shows French text, which translates to English as 'BLOOD MESSAGE FOR THE FRENCH GOVERNMENT'. It then shows Gourdel kneeling with his arms tied behind his back before four masked militants. Two have assault rifles. Gourdel appears to have a gash on the front of his throat. He appears calm. One of the men, reading from a script, says: 'Here is criminal France that is full of hatred for Muslims, coming to us with a new dress. The aggression on the Muslims in Mali was not enough for it, and before that in Algeria, where it destroyed and sowed corruption in the land, violated honor, fought whoever converted to Islam with its laws, prevented the hijab, spread vice and corruption, and killed the Muslims and displaced the weak. 'And today it refused to see the Shariah of Allah be applied in the land, the implementation of proscribed punishments, and the religion be spread. 'So it came with its horses and men to participate in this Crusader war under the pretext of terrorism, as they allege.' 'Let the French people know that their blood is cheap for their president, and it is the same as you made the blood of the Muslim women and children cheap in Iraq and Sham [Syria] and other countries. 'Your blood has been cheapened as an exact recompense.' The militants then push the victim on his side and hold him down. The video does not show the beheading, but a militant holds the head up to the camera afterwards. Just before the militants gave their statement, the Frenchman briefly addressed his family. Advertisement

Mr Gourdel's murder came just 30 minutes after Obama addressed efforts to combat ISIS and its affiliates at a meeting of the UN General Assembly.

The U.S. president said ISIS understood only 'the language of force' and called on those who have joined up to fight with the group to 'leave the battlefield while they can'.

Mr Obama recounted IS atrocities against women and religious minorities in areas of Iraq and Syria which the group controls, and described the beheading of hostages including British aid worker David Haines as 'the most horrific crimes imaginable'.

The US president said: 'No God condones this terror. No grievance justifies these actions. There can be no reasoning - no negotiation - with this brand of evil.'

Experienced: Mr Gourdel was a professional mountaineering guide and amateur photographer. Although he enjoyed spending time in remote locations around the world, he was always extremely careful, friends said

Hunt: Yesterday's warning video prompted some 1,500 Algerian forces to comb through the restive, Tizi Ouzou region in the east of Algeria - desperately trying to save Mr Gourdel before it was too late

Dangerous location: Mr Gourdel was seized on Saturday while hiking in the heart of Algeria's Djurdjura National Park (pictured). The mountains have been a sanctuary for radical Islamists loyal to Al Qaeda since the 1990s

An IS militant fires a rocket propelled grenade launcher during fighting near the Syrian Kurdish town of Ain al-Arab, known as Kobane by the Kurds

An IS militant firing a cannon mounted on a truck during fighting near the Syrian Kurdish town of Ain al-Arab,

Barrage: An IS militant fires a heavy machine gun during the fighting. Some 140,000 mainly Kurdish refugees have now crossed the border into Turkey after the militants moved on the town of Ain al-Arab

Meanwhile, airstrikes in northern Syria killed the 'world's most wanted terrorist' before his band of Islamist militants were able to carry out deadly 'toothpaste tube bomb attacks' on the U.S. and Europe, American officials believe.

Muhsin al-Fadhl, 33, was identified as the leader of the Al Qaeda-affiliated Khorasan Group - a radical terror collective specializing in intercepting Western jihadists on their arrival in Syria, and training them to carry out deadly bomb attacks on targets in their home nations.

'WE'VE KILLED WORLD'S MOST WANTED TERRORIST': AMERICAN OFFICIALS BELIEVE MUHSIN AL-FADHLI DIED IN SYRIAN AIRSTRIKES Airstrikes in northern Syria killed the 'world's most wanted terrorist' before his band of Islamist militants were able to carry out deadly 'toothpaste tube bomb attacks' on the U.S. and Europe, American officials believe. Muhsin al-Fadhl, 33, was identified as the leader of the Al Qaeda-affiliated Khorasan Group - a radical terror collective specializing in intercepting Western jihadists on their arrival in Syria, and training them to carry out deadly bomb attacks on targets in their home nations. As well as an American and Arab coalition hitting targets relating to ISIS militants in Syria yesterday, the U.S. air force also independently struck Khorasan as intelligence suggested the group were nearing 'the execution phase' of a terror atrocity against a Western target that could have rivalled 9/11. Details of the alleged death of al-Fadhl emerged this afternoon from a U.S. military official speaking on condition of anonymity. Despite his relatively young age, the Kuwait-born militant was an Al Qaeda veteran; joining the terror group as a teenager and becoming so close to its leadership that he was among a select few with prior knowledge of the 9/11 attacks in America, despite having only just turned 20 at the time. Advertisement

As well as an American and Arab coalition hitting targets relating to ISIS militants in Syria yesterday, the U.S. air force also independently struck Khorasan as intelligence suggested the group were nearing 'the execution phase' of a terror atrocity against a Western target that could have rivalled 9/11.

British Prime minister David Cameron today held an extraordinary meeting with Iranian president Hassan Rouhani to seek help in defeating ISIS militants.

It is the first face-to-face talks for 35 years between the leaders of the two countries which have been at loggerheads over Tehran's nuclear policy.

However, Mr Cameron made clear that a global alliance is needed to tackle the rise of ISIS, as he prepares to recall Parliament on Friday for a vote on RAF air strikes in Iraq.

Mr Gourdel's death was eventually confirmed by terrorism watchdog SITE Intelligence Group this afternoon.

The hunt for Mr Gourdel came a day after French President Francois Hollande vowed not to give in to the jihadists' demands while on official trip to New York.

'As grave as this situation is, we will not give in to any blackmail, any pressure, any ultimatum, no matter how odious, how despicable,' he said.

'What is at stake here is our liberty, our security and sovereignty. No terrorist group can influence the will, position or freedom of France,' he added.

Mr Gourdel, who lived in the southern French city of Nice, only arrived in Algeria on Saturday and was seized the following day while hiking in the heart of the Djurdjura National Park.

The area's dense forests, deep gorges and picturesque lakes were once a major draw for tourists.

Block: David Cameron speaking at a meeting of the UN Security Council today which passed a resolution to require all countries to stop the transport and recruitment of would-be fighters

Powers: The meeting was designed to discuss in detail how to tackle the growing threat of ISIS

Foreign fighters: US President Barack Obama chaired the meeting (pictured with US UN ambassador Samantha Power advising him)

However, the mountains became a sanctuary for Islamists in the 1990s, who later swore allegiance to Al Qaeda, and security forces have been unable to dislodge them.

A passionate photographer and mountaineer, Mr Gourdel liked going off the beaten track, though he was always careful, his friends said.

'I often bump into him in the mountains and he always goes to little-known areas of the massif, never on the major routes where there are people,' said Michel Ingigliardi, his friend of 30 years in Saint-Martin-Vesubie, a village nestled deep in the French Alps outside Nice.