LONDON/PARIS (Reuters) - A Frenchman is believed to have been among Islamic State jihadists appearing on a video showing the severed head of U.S. aid worker Peter Kassig, but a British man denied earlier reports his medical student son was there too.
Sunday's announcement of Kassig's death, the fifth such killing of a Western captive by Islamic State, formed part of a video that also showed the beheadings of at least 14 men Islamic State said were Syrian military pilots and officers.
France's interior minister said analysis by the DGSI security service suggested that one of the men shown herding prisoners to the execution site was Maxime Hauchard, 22, a French Muslim convert from the Normandy region.
"This analysis suggests with a very high probability that a French citizen could have directly participated in carrying out these abject acts," Bernard Cazeneuve told journalists.
French security services were analysing the footage to determine if a second fighter was also French, but Paris prosecutor Frederic Molins told reporters it was too early to say.
The parents of Kassig, a 26-year-old medic and former U.S. Army Ranger who took the name Abdul-Rahman Kassig after his conversion to Islam, called for prayers for captives in Syria and Iraq in a brief statement on Monday at their Indianapolis church.
"If a person can be both a realist and an idealist, then that's Peter," said Kassig's mother, Paula Kassig, reading words written about her son by one of his former teachers. "Peter has earned the right to be both.... Peter's life is evidence that he's been right all along; one person can make a difference."
The Kassigs had repeatedly appealed to Islamic State to spare their son, who had begun converting to Islam before his capture in Syria in October 2013. They said his conversion was a sincere process.
French judges opened a preliminary investigation last year against Hauchard on suspicion he was conspiring to commit terrorist acts, the charge commonly levied against citizens who have fought with Islamist militants.
In an interview with French television in the summer, Hauchard said his goal in joining Islamic State was to become a martyr.
France is part of a coalition carrying out air strikes on Islamic State. It toughened anti-terrorism laws this year to stop citizens going to Syria and prevent young Muslims from becoming radicalised.
Briton Ahmed Muthana was quoted by the Daily Mail as saying that his 20-year-old son, Nasser Muthana, appeared to be among the group of jihadists seen in the video.
"I cannot be certain, but it looks like my son," Ahmed Muthana was quoted by the newspaper as saying.
But speaking to reporters on Monday outside his house in the Welsh capital, Cardiff, he said: "That is not my son, the nose is different, it does not look like my son."
"I have not seen my son since November 2013, but that is not my son; the nose is different," Muthana said. He also told Reuters by telephone that the man shown in the video was not his son.
British Prime Minister David Cameron will chair a meeting of the government's emergency response committee, Cobra, in the next 36 hours to receive a briefing from intelligence and security officials in light of the latest video, his spokesman said.
Britain’s security threat level was raised to its second-highest in August because of the risks posed by Islamic State fighters returning from Iraq and Syria.
Islamic State includes thousands of foreign combatants in Iraq and Syria and has become a magnet for jihadists from Europe and North America.
IS has released videos of the beheading of two American and two British men, which feature a masked, black-clad militant brandishing a knife and speaking with an English accent, who has been dubbed "Jihadi John" by British media.
Sunday's video showed all of the killers unmasked, with the exception of the black-clad militant, and the Daily Mail said the man who appeared to be Nasser Muthana was standing alongside Jihadi John. Muthana appeared in a video in June urging Muslims to join IS.
(Reporting by Rebecca Naden and Ahmed Aboulenein in Cardiff, Kate Holton and Paul Sandle in London, Nicholas Vinocur in Paris and Brent Smith in Indianapolis; Editing by Giles Elgood, Peter Graff, Sophie Walker, Peter Cooney and Howard Goller)