A second French militant has been identified in the video showing a beheaded American aid worker and the deaths of Syrian soldiers, France's president said Wednesday, calling for vigilance on "how these young people can be indoctrinated."

Speaking in Canberra, Australia, President Francois Hollande said Wednesday that the roles of the two men have yet to be determined precisely.

"All we can say for now is that there are two French people who have been identified," Hollande said.

Government officials on Monday identified 22-year-old Maxime Hauchard among the Islamic State militants see in the video announcing the death of aid worker Peter Kassig. Agnes Thibault-Lecuivre of the Paris prosecutor's office said there was a "strong presumption" that Michael Dos Santos, a 22-year-old from the Paris suburbs who like Hauchard left for Syria in August 2013, was among those wielding knives in the video.

European jihadis have taken an increasingly visible role in propaganda by the Islamic State group, as the militants try to demonstrate a global profile. France is a significant source of its foreign recruits, with hundreds who have made the trip and about 1,100 under surveillance, officials said this week.

Western officials fear that an Islamic militant with a European passport could return from the war zone with dangerous skills and the means to reach more two dozen countries undetected. More than 2,000 Europeans are believed to be among an estimated 15,000 foreigners who have joined the fighting, most of them for the Islamic State group, according to various government and analyst estimates.

The Islamic State group has declared a self-styled Islamic caliphate in areas under its control, which it governs according to its violent interpretation of Shariah law.