Algerian militants have released a video that appears to show them killing Frenchman Herve Gourdel, who was kidnapped on Sunday, in what the group said was a response to France's action against Islamic State militants in Iraq.

The video shows Gourdel, a 55-year-old tourist from Nice, kneeling with his arms tied behind his back before four masked militants who read out a statement in Arabic criticizing France.

They then pushed him on his side and held him down. The video does not show the beheading, but a militant holds the head up to the camera.

French President Francois Hollande on Wednesday confirmed the death of Gourdel,.

"Our compatriot has been murdered," Hollande told reporters ahead of his speech to the U.N. General Assembly in New York.

The Caliphate Soldiers, a splinter group linked to Islamic State militants in Iraq and Syria, had on Monday published a video claiming responsibility for the abduction and showed the man identifying himself as Gourdel.

French Foreign Minister Laurent Fabius had said then that the taking of a French hostage would not deter French participation in a U.S.-led coalition of nations against Islamist State militants.

The kidnapping had come after Islamic State spokesman Abu Muhammad al-Adnani urged the group's followers to attack citizens of the United States, France and other countries that joined the coalition to destroy the radical group.

France launched its first air strikes targeting Islamic State targets in Iraq on Friday. It has said all must be done to rid the region of the group.

Western diplomats and intelligence sources say they believe there are fewer than 10 Western hostages still held by Islamic State. The group has recently killed two Americans, James Foley and Steven Sotloff, and one Briton, David Haines, and threatened to kill another Briton, Alan Henning.

The kidnapping was one of the first abductions of a foreigner by militants in Algeria since the North African country ended its decade-long war with Islamist fighters in the 1990s.