French authorities have identified one of the men seen in a video by the Islamic State in Iraq and the Levant (ISIL) group, purportedly showing the beheading of US aid worker Peter Kassig and 12 Syrian military personnel, as one of its nationals.
The killing of Kassig and the simultaneous beheadings of the military personnel in the video sparked global outrage, with US President Barack Obama calling it "an act of pure evil".
It was the latest in a series of atrocities by the ISIL, which has seized control of large parts of Iraq and Syria.
The video showed the Syrian men kneeling on the ground each before a separate executioner, whose faces were uncovered.
"It [the video] has allowed us to identify one of the jihadis as French citizen Maxime Hauchard," Paris Prosecutor Frederic Molins told reporters on Monday.
"There is the possible existence of a second Frenchman, but it is too early to say."
|Interview: UN Commissioner for Human Rights on Kassig beheading.
Molins said one of Hauchard's contacts "had been arrested in France last week and charged with terrorism-related offences", adding that he was known to intelligence services after twice travelling to Mauritania to attend Salafist Koranic centres.
Interior Minister Bernard Cazeneuve earlier said analysis by the security services suggested that Hauchard, 22, a French Muslim convert from the Normandy region, was one of the men herding prisoners to the execution site.
Thousands of foreign fighters, including Westerners, have flocked to Iraq and Syria to join ISIL.
'To become martyr'
Interviewed in July by French TV station BFM via Skype, Hauchard said he had decided to join ISIL after watching videos online.
"The personal objective of everyone here is [to become a] shahid [martyr]. That is the greatest reward," he said.
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Kassig, who took the name Abdul-Rahman after converting to Islam, was captured last year and became the fifth Western hostage beheaded by ISIL after two US reporters and two British aid workers.
A US-led coalition is targeting the Islamic State group in airstrikes in northern Syria, supporting Western-backed Syrian rebels, Kurdish fighters and the Iraqi military.
The US announced that a total of 31 airstrikes had been carried out between November 14-17 against Islamic State group targets.