A group claiming links with Islamic State (Isis) threatened last night to kill a French hostage in Algeria within 24 hours if France continued its airstrikes in Iraq.

A video posted online said that Hervé Pierre Gourdel, 55, from Nice, who was seized while hiking in mountains west of Algiers on Sunday, would be killed if the “infidel French” did not call off their offensive against Isis.

News of the abduction came after Isis called on Muslims to kill citizens of countries taking part in the US-led anti-jihadist coalition in Iraq and Syria.

The Algerian group Jund al-Khilafah — Soldiers of the Caliphate — which has pledged allegiance to Isis, said that it carried out the kidnapping in a mountainous region where the local affiliate