French officials have identified a second Frenchman among the militants in a video showing the severed head of an American aid worker and the beheadings of at least 18 Syrian soldiers.
President Francois Hollande said Wednesday during a visit to Australia that two French nationals are in the video released by the Islamic State group but did not give additional details.
Investigators said they believe the second man was a 22-year-old from a Paris suburb who traveled to Syria about a year ago.
On Monday, officials identified the first man in the video as Maxime Hauchard, also 22, a convert to Islam who went to Syria last year.
The Paris prosecutor's office said the second French suspect was also a Muslim convert who traveled to Syria in August 2013. The second suspect was known to intelligence services, it said.
Hollande highlighted the danger of what he called young people being brainwashed by militants abroad. Earlier this year, France toughened its anti-terrorism laws to stop citizens from going to Syria and prevent young Muslims from becoming radicalized.
Thousands of Western volunteers have joined the Islamic State group, which has taken control of large swathes of both Syria and Iraq. More than 1,130 French citizens are involved in jihadi cells linked to the two countries, with 376 nationals in the region.
A report published by the CPDSI, an institute created specifically to study radicalization linked to Islam in French society, showed on Tuesday that the majority of those that had turned to radical Islam were from middle class families, originally atheist and under 21.
The Islamic State group has released multiple videos showing the executions of American and British hostages. Abdul-Rahman (Peter) Kassig was the American aid worker seen in the latest video.
FILE - This undated photo shows Peter Kassig leaning against a truck at an unknown location.
Kassig was taken captive 13 months ago while doing humanitarian work in war-torn Syria. U.S. President Barack Obama on Sunday condemned his killing, calling it "an act of pure evil."
The British-based Syrian Observatory for Human Rights said the Islamic State group has now executed more than 1,400 people in Syria since the end of June, when it declared a caliphate over vast territories it controls in Iraq and Syria.
Also Wednesday, France said it is sending six fighter jets to the Middle East as it seeks to increase its airstrikes against Islamic State targets in Iraq.
French Defense Minister Jean-Yves Le Drian told parliament the six Mirage jets will be based in Jordan to reinforce French aircraft that are already in the region.
The United States, Britain and France are all taking part in airstrikes against the militant group in Iraq, with U.S. planes also bombing Islamic State targets in neighboring Syria.
U.S.-led forces conducted six airstrikes in Syria against Islamic State fighters and one U.S. airstrike against a network of veteran al-Qaida operatives, sometimes called the "Khorasan Group," over a two-day period ending Wednesday, according to U.S. Central Command.
Coalition forces conducted 24 airstrikes in Iraq during the same period, with 13 of those airstrikes near Kirkuk, Centcom said on Wednesday.