This man, believed to be Briton Nasser Muthana, appears in the sickening video which shows the decapitated body of an American aid worker

The father of a British medical student believed to be standing shoulder-to-shoulder with 'Jihadi John' in a new beheading video said today he should be executed if he is involved.

Ahmed Muthana, 57, from Cardiff, has disowned his son Nasser, 20, who appears to be among 16 camouflaged IS fighters filmed beheading 17 Syrian soldiers in the desert alongside Peter Kassig.

Mr Muthana said if Nasser is a member of the killing squad he should be executed, adding it should be 'a head for a head', he told the Evening Standard.

He said: 'I am like any other father. I am trying not to believe it is my boy but it looks like him.

'But I am not going to make excuses for him. He is a grown man and he must face up to what he has done.'

The sickening video that was on YouTube for an hour yesterday morning also shows the decapitated body of Peter Kassig, a 26-year-old American aid worker.

Ahmed Muthana said: 'I cannot be certain but it looks like my son. He must fear Allah now for killing people. How can he expect to face Allah if he is killing human beings?'

Asked if he would forgive his son if he returned home to Cardiff, the 57-year-old replied: 'No, he must be mentally ill – either that or there is something else not right.'

Mr Muthana tried to shield his wife Samira, 55, from the sickening video showing her eldest son in the slickly produced propaganda video.

Father-of-four Mr Muthana said: 'She saw it on the television and she asked me what was going on.

'It looks like Nasser but he has lost a lot of weight... He was big, maybe 18 stone when I last saw him almost exactly a year ago, but he looks thinner in the face in the video.'

He added: 'I have not heard directly from either of my sons since they went. But Aseel was in touch with my cousin earlier this year in the Yemen through social networking.

'They are my sons and they are gone and I don't want them back. No father wants to disown their children but I have no choice. That is the way it is.'

Analysts believe the murder video is an attempt by Islamic State to provoke the West into an all-out assault and 'final battle'.

As Jihadi John, the British leader of the killing squad, warned David Cameron of slaughter on our streets:

The former Chief of the General Staff said Britain may need to 'think the unthinkable' and send ground troops to take on Islamic State forces;

The man believed to be Muthana is circled in the latest ISIS beheading video stood right next to Jihadi John

The British jihadists's father said while he cannot be sure, one of the men looks like his son. Muthana appeared in an ISIS propaganda video earlier this year (left) after leaving his hometown Cardiff (right)

Mr Cameron said the beheadings underlined the 'deplorable depths' the 'depraved' terrorists were prepared to go to;

The acts were described as '13th-century barbarism' by former PM John Major;

Friends of Mr Kassig said he may have refused to make a propaganda statement before he was murdered;

Barack Obama described Mr Kassig's murder as an 'act of pure evil'.

The footage showed John and 15 other unmasked extremists brutally decapitating Syrian army hostages.

Speaking with his distinct British accent, John issued a blood curdling threat to slaughter people on the streets of Britain.

The Foreign Office said yesterday it was investigating unconfirmed claims that John had been recently wounded in an airstrike by the Americans.

It is unclear when the horrific but slickly-produced film was shot but it is markedly more graphic than previous videos and the final act of beheading a long line of hostages is not blacked out. Mr Kassig, who converted to Islam in captivity, becomes the fifth Western victim to be beheaded.

Last night, the former Chief of the General Staff, Lord Dannatt, said: 'We need to keep all options open if we are to defeat IS. Are we just going to wish this away, or are we going to take action?'

The Foreign Office confirmed they were 'looking into' claims that Muthana, who left his family to train with extremists in Syria, was one of the militants in the footage.

Muthana was exposed as a terrorist in training after he appeared in a recruitment video for the insurgent group in June, devastating the family he left behind in Cardiff after it was circulated on the internet.

A prospective medical student, he was joined in Syria by his younger brother Aseel, 17, who has spoken of his willingness to die fighting. After arriving in the country, Muthana threatened to use his terror 'skills' when he returned to the UK.

Charlie Winter, from the Qulliam Think Tank, said: 'It looks like Nasser Muthana is in the video. The video is far more graphic than other videos. It is reflective of perhaps IS trying to be defiant in the face of increased pressure.

'Things aren't going well for them at the moment and this is a message of defiance and provocation.'

In the sickening video a group of Syrian soldiers are marched to their execution site by Islamic State militants

British medical student Nasser Muthana lived in this street in Cardiff before he fled for Syria

In the video, John branded the Obama administration as 'liars' for not withdrawing from Iraq, adding: 'The spark has been lit here in Iraq and its heat will continue to intensify by Allah's permission until it burns the crusader army in Dabiq.

'And here we are, burying the first crusader in Dabiq. Eagerly awaiting for the remainder of your armies to arrive.'

This morning top security official said a Frenchman suspected of joining ISIS is believed to be among the killers in the gruesome video.

Interior Minister Bernard Cazeneuve said Monday that there is a 'strong possibility' that Maxime Hauchard is among the group of Islamic extremist fighters in the video released over the weekend.

Cazeneuve said authorities are analyzing the video and have been investigating Hauchard, who is about 22 years old and from west of Paris.

French citizens make up the largest contingent of European jihadi fighters who have joined extremists in Syria and Iraq. According to the Paris prosecutor's office, about 1,100 people have been placed under surveillance, and 95 people face charges.

Analysts said the change of video location to Dabiq – and not somewhere on the outskirts of Raqqa as before – suggested that John and hostages were being moved frequently to avoid coalition air strikes and to thwart rescue attempts.

A friend of Mr Kassig said the lack of a statement suggested he had defied his captors.

Michael Downey, a close friend from Beirut, said: 'I think he refused. He was a man of principle and wouldn't give into intimidation from thugs. He never took the easy route.'

More barbaric than ever, video that seeks to trigger an invasion

The horrifying video of the mass murder of Syrian soldiers and an American aid worker is very different from other Islamic State propaganda films.

Posted yesterday morning, it shows how the jihadists are seeking to heighten the disgust they provoke.

Security and military analysts believe this new tactic is a plot to lure Western and other forces into a full-scale ground offensive IS leaders think they can win.

Unmasked: The 16 followers of Jihadi John prepare to behead the Syrian soldiers they have held hostage. Nasser Muthana from Cardiff is to the right of John, who is dressed in black with a balaclava

The analysts reckon IS is already reeling from air attacks that have stopped it taking the key Syrian border town of Kobane.

The murder of US aid worker Peter Kassig is not shown in the latest film – thought to feature UK medical student Nasser Muthana– and he does not deliver a final message as other hostages have.

There is also no announcement of the name of the next victim.

And for the first time the Islamic militants give away their location – showing what is believed to be Dabiq, a town in northern Syria – in the video's background.

PROPAGANDA MASQUERADING AS A HISTORY LESSON

Lasting 15 minutes and 53 seconds, the video – titled 'Although the disbelievers dislike it' – starts with a documentary-style history of Islamic State since the invasion of Iraq by western allies in 2003.

It is in a different style from the rest of the footage, with more sophisticated graphics, and a treatment often used for major 'state of the nation' productions.

There are scenes of bombings, summary executions and graphic video footage of dead civilians lying in the streets. It also shows what appears to be a dead child lying on a bed covered in blood.

Some of the footage of the bombings has not been seen before, though other scenes showing the summary killings of suspected Iraqi soldiers has. It is designed to incite supporters and operatives back in the UK by justifying their actions and setting the stage for the next clip.

Still covered up: Jihadi John has so far shown the world only his eyes

THE RETURN OF JIHADI JOHN WITH 16 FOLLOWERS

Filmed in the desert, the self-declared murderer, known as Jihadi John, is seen leading a line of Syrian troops to their deaths. A few paces behind him – and in the middle of a 16-strong line of Islamist jihadists said to be from over six countries – is the man believed to be Muthana, a 20-year-old from Cardiff.

Like the other jihadists he is unmasked. John however keeps to his habit of showing only his eyes.

Muthana clutches the scruff of the neck of a Syrian soldier, whose hands are bound with plastic ties.

But while the other militants have expressionless faces – this young bearded man looks menacingly into the distance. Taking the lead from John and those in the line before him, he brandishes a military knife taken from a box of weapons.

The chilling sound of a blade being drawn can be heard above the sound of Islamic music in the background.

The prisoners are not wearing Guantanamo-style orange jumpsuits, as in previous videos, but are dressed in black trousers and shirts.

John, who has leather shoulder holsters for hand guns and a balaclava-style mask, takes centre stage. His appearance would seem to confirm his seniority and status as 'chief executioner' of Islamic State. The man thought to be Muthana stands to his right. John delivers his message to America and Britain before an eerie silence during which the camera zooms in on the faces of the killers, who remain impassive throughout.

The scene then focuses on John – who begins to cut his prisoner's neck – quelling suspicion that he himself did not actually perform the previous beheadings. Unlike the apparent murders of Western hostages, in which the camera cuts away at the moment their throats are cut, the killings of the soldiers are shown in full.

The camera zooms in on Jihadi John and his victim who, in his final agonising moments, closes his eyes. John then looks threateningly into the camera while still holding the knife. The next clip shows a knife slicing into the necks of Syrian soldiers followed by a stream of blood that turns the sand red.

The image after that shows the soldiers' heads on top of their bent-over bodies.

The mass beheading is a new departure because previous mass executions have been undertaken using guns.

The fact that John's accomplices revealed their identities suggests they have no intention of returning to their home countries. A caption refers to them as 'hungry lions whose drink is blood and play is carnage'.

SITE OF FINAL BATTLE WITH 'CRUSADERS'

As with the other clips, it is not clear when the final scene was actually filmed – though it is claimed to have been shot in Dabiq in northern Syria.

John's face is in shadow and it is hard to make out – but his mannerisms seem to be the same as in other videos. He talks with his now-familiar London accent.

An image is shown of a man's head lying on the ground next to a man wearing desert boots – before the camera jumps to Jihadi John.

Peter Kassig is pictured while working as an aid worker in Syria before his capture. His murder is not actually shown in the latest film and he does not deliver a final message as other hostages have

In the sickening video, only the severed head of American hostage Peter Kassig (pictured) is seen

While his death has not been verified, John says: 'This is Peter Edward Kassig, a US citizen of your country.

'Peter, who fought against the Muslims in Iraq while serving as a soldier under the American army, doesn't have much to say. His previous cellmates have already spoken on his behalf.'

Mr Kassig's beheading is not shown – nor does he give a statement spurting IS propaganda. He may have refused to do so – or it may mark a change in tactics by the militants.

A dateline on the video says it was shot in Dabiq, near Aleppo, a place cherished by Islamic State militants.

According to one reading of Islamic tradition, there will be a final battle there between good and evil – in this case Muslim and Christian armies.

The 'Western Crusaders' will eventually be destroyed, according to the reading.

Analysts said the change of location may also suggest that John and the hostages were being moved more frequently than normal to avoid coalition air strikes and to thwart rescue attempts.

WHAT ABOUT THE BRITON JOHN CANTLIE?

Unlike previous Islamic State beheading videos of Western hostages, there was no reference to further deaths.

In the earlier films John had warned of the next hostage to die, showing a clip of them on their knees and wearing an orange jumpsuit.

The British hostage John Cantlie is currently being held by Islamic State and has appeared in propaganda videos for the terror group

He has used the prospect of another Western death as a warning to the US and Britain against using military force in Iraq and Syria.

John Cantlie, the British journalist currently being held by the Islamic State, has featured in several propaganda videos but is yet to be named by his captors as the next to be killed.



