A terrorism watchdog says Algerian extremists allied with the Islamic State group have killed a French hostage.

A group calling itself Jund al-Khilafah said after abducting Herve Gourdel on Sunday that he would be killed within 24 hours unless France ended its airstrikes against Islamic State fighters in Iraq. The French government has insisted it will not back down.

U.S. terrorism watchdog SITE Intelligence Group says Jund al-Khilafah released a video online Wednesday saying Gourdel has been killed. He was a 55-year-old mountaineering guide from Nice. The French government would not immediately comment.