Paris - France said on Monday there was a very strong likelihood that an Islamic State militant who appears on a beheading video released by the group at the weekend was a 22-year-old French citizen.
The 15-minute video posted online shows the decapitations of at least 14 men whom Islamic State said were pilots and officers loyal to Syrian President Bashar al-Assad.
The video also shows the severed head of US aid worker Peter Kassig.
France's interior minister said analysis by its DGSI security service suggested that one of the men shown herding prisoners to the execution site was Maxime Hauchard, a Frenchman from the northern Eure region who left for Syria in August 2013.
"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.
The disclosure came hours after a father in Britain said he believed his son, a British medical student, was in the Islamic State squad filmed beheading the soldiers.
Hundreds of Western volunteers have joined the ranks of Islamic State insurgents in Syria and Iraq.
The French and British governments have said that any citizen participating in executions would face consequences for their acts.
French authorities have said that about 1 000 citizens have joined Islamist factions in Syria.
Judges last year opened a preliminary investigation against Hauchard on suspicion that he was participating in a conspiracy to commit terrorist acts, the charge commonly levied against citizens who have fought with Islamist militants.
Hauchard, whom French media have said was known in his home town as "friendly, easygoing" and without a criminal record, was interviewed by BFMTV in the summer saying that his goal in joining Islamic State was to become a martyr. - Reuters