AID worker Peter Kassig was the victim featured in the latest beheading video released by the Islamic State, President Barack Obama confirmed last night.

Footage showing the US aid worker's death at the hands of IS militant known as Jihadi John was released amid reports that the infamous extremist had been injured in an allied air strike.

The masked fanatic, who is thought to be British and speaks with a London accent, is believed to be responsible for the killings of Scots aid worker David Haines and taxi driver Alan Henning, from Salford, along with American journalists James Foley and Steven Sotloff.

In the latest video, posted online yesterday, he declared that he had taken the life of humanitarian Abdul-Rahman Kassig - also known as Peter.

It is unclear from the footage whether it was shot before or after the US-led airstrike on a summit attended by IS commanders on November 8. It has been claimed the British jihadist was taken to hospital after narrowly escaping death in the raid on the town of Al Qaim, in Anbar province, near Iraq's border with Syria.

The UK Foreign Office confirmed it was aware of reports the wanted terrorist had been hit, but was still trying to verify them.

Mr Obama confirmed the death of Mr Kassig and offered his condolences to the aid worker's family.

His parents - who had appealed to IS to free their son - have called for restraint in the coverage of the graphic 16-minute video.

Ed and Paula Kassig, from ­Indianapolis, said: "The family respectfully asks the news media to avoid playing into the hostage takers' hands and refrain from publishing or broadcasting ­photographs or video distributed by the hostage takers.

"We prefer our son is written about and remembered for his important work and the love he shared with friends and family, not in the manner the hostage takers would use to manipulate Americans and further their cause."

Mr Kassig, 26, served with the US military and was deployed to Iraq in 2007. Following an honourable discharge, he moved to Beirut and set up a medical charity that specialised in delivering aid to ­refugee camps. An only child, his love of the Middle East led him to convert to Islam. He was taken hostage by IS in October 2013 during a trip to deliver food and medical supplies in eastern Syria.

In contrast to previous videos, the latest release does not show the act of beheading. Only Mr Kassig's decapitated head is filmed, along with a diatribe by 'Jihadi John' against western forces. It does not end by identifying other ­Western captives who are under threat of death, as previous releases have.

However, the video does feature what appears to be the mass beheading of about 18 Syrian soldiers captured by the group. The militants warn US soldiers will meet a similar fate.

Prime Minister David Cameron warned anyone considering ­travelling to Syria or Iraq to fight for the militant group was "putting themselves in harm's way" but declined to comment on specific military operations in the region.

Speaking at a press conference at the G20 summit in Australia, Mr Cameron said: "You should be in no doubt I want Jihadi John to face justice for the appalling acts that have been carried out in Syria, but I wouldn't make any comment on individual issues and strikes."

Meanwhile, British combat troops could be required to fight in Iraq and Syria to eradicate the IS threat, a former head of the Army has said.

General Lord Dannatt said ­Western leaders might have to "think the unthinkable" and send in troops if the combination of air strikes and local forces was unable to counter the jihadis.

The former chief of the general staff said: "I don't see that ­happening in a great rush, there's no appetite for it, there's no political appetite for it.

"But we have got to keep all options open if we are serious about meeting that strategic objective of defeating and destroying Islamic State."