Several outlets are reporting that video has surfaced of an Islamic State-aligned group in Algeria beheading a French hostage for his country’s support of military efforts in Iraq and Syria.

Jund al-Khilafah militants captured Hervé​ Pierre Gourdel, 55, on Sunday while he was hiking Algeria’s mountains, and released a video on Monday in which they give French president François Hollande “24 hours to stop its offensive against the Islamic State” or the hostage will be killed. In the most recent video released, Gourdel is reportedly shown kneeling before a group of fighters and is held down before the screen goes dark; the video returns and appears to show the militants holding his head above his body.

ABC News reports that the French Foreign Ministry is still authenticating the video.

In an earlier statement, Jund al-Khilafah said it was answering the Islamic State’s recent call for its supporters to capture Westerners from countries in the fight against the group.

UPDATE: Hollande has confirmed Gourdel’s death, according to the Daily Mail. “Our compatriot has been murdered,” he told reporters at the United Nations General Assembly in New York.