An Islamic State-linked group in Algeria released a video on Wednesday claiming to have killed a Frenchman captured in the Tizi Ouzou area over the weekend. French authorities have not yet confirmed the authenticity of the video.

Militants linked to the Islamic State (IS) group beheaded a Frenchman abducted in Algeria in a video posted online on Wednesday, after giving France a 24-hour deadline to stop its assault on IS militants in Iraq.

Hervé Gourdel, a 55-year-old mountain guide from the southern French city of Nice, was kidnapped on Sunday by the Jund al-Khalifa group while he was hiking in the Tizi Ouzou area of northeastern Algeria.

The Jund al-Khalifa – variously translated as the “Soldiers of the Caliphate in Algeria” or “Caliphate Soldiers of Algeria” – emerged earlier this month, when a regional commander of Al Qaeda in the Islamic Maghreb (AQIM) released a statement announcing that he had broken away from al Qaeda and had sworn loyalty to IS group.

The group released a video on Monday night showing Gourdel flanked by two hooded militants and pleading with French President François Hollande to “do everything to get me out of this bad situation”.

His captors said they were giving France 24 hours to stop its operations against IS targets in Iraq.

France has joined the US in carrying out air strikes against the IS group, which has seized swathes of Iraq and Syria. On September 19, French fighter jets bombed a fuel and weapons depot outside the northern Iraqi city of Mosul.