Algiers (AFP) - Jihadists linked to the Islamic State group beheaded a Frenchman abducted in Algeria in a video posted online Wednesday, after Paris rejected their demand to halt air strikes in Iraq.
President Francois Hollande condemned the "cruel and cowardly" murder of Herve Gourdel and said it would only strengthen France's resolve to pursue its air war against the Islamic State group.
The 55-year-old was kidnapped on Sunday by Jund al-Khilifa, or "Soldiers of the Caliphate," while hiking in a national park that was once a magnet for tourists but later became a sanctuary for Islamists
His beheading followed France's rejection of the group's 24-hour ultimatum to halt air raids in Iraq -- part of a US-led campaign against IS.
Hollande vowed France would not be deterred from continuing its military action.
"This aggression only reinforces my determination," he said, speaking on the sidelines of the UN General Assembly.
He said he would convene a special security meeting on Thursday to discuss Gourdel's murder and vowed to hunt down his killers.
"The perpetrators of this odious crime must be punished," he said.
The video, entitled "A Message with Blood to the French Government", employs a similar style to those used in previous videos by IS showing the beheadings of three Western hostages.
It begins with a clip of Hollande at a press conference where he announced strikes against IS in Iraq.
The video then shows Gourdel on his knees with his hands behind his back in front of four armed militants with covered-up faces.
The Frenchman briefly expresses his love for his family before one of the jihadists reads a speech in which he denounces the actions of the "French criminal crusaders" against Muslims in Algeria, Mali and Iraq.
The jihadist says the beheading is to "avenge the victims in Algeria... and support the caliphate" proclaimed by IS in Iraq and Syria.
The United States has built a coalition of more than 50 nations to fight the IS organisation, after the jihadists seized large parts of Syria and Iraq and committed widespread atrocities, including beheadings and crucifixions.
France has ruled out joining military operations in Syria, where a US-led coalition began strikes against IS on Tuesday.
- 'Show no weakness' -
Prime Minister Manuel Valls, in a speech Wednesday that kicked off a parliamentary session about France's engagement in Iraq, vowed not to give in to blackmail.
"If we show weakness in the face of this threat, we encourage these cowards to continue their work of death," he said.
"We will stay committed... for as long as is needed for the Iraqi army to gain the upper hand over Daesh," he added, using an alternative name for IS.
"It's not our intervention that is exposing us to terrorism. The threat has been there for a long time. And that's why we are acting," Valls said.
Gourdel only arrived in Algeria on Saturday and was seized the following day while hiking in the heart of the Djurdjura National Park, whose dense forests, deep gorges and picturesque lakes were once a major attraction for tourists.
The mountains became a hideout for Islamists in the 1990s who later swore allegiance to Al-Qaeda, and security forces have been unable to dislodge them.
A passionate photographer and mountaineer, Gourdel liked going off the beaten track, though he was always careful, his friends said.
"I often bump into him in the mountains and he always goes to little-known areas of the massif, never on the major routes where there are people," said Michel Ingigliardi, his friend of 30 years in Saint-Martin-Vesubie, a village nestled deep in the French Alps outside Nice.
"Going to far-away isolated countries is consistent with his personality."
The group that abducted him was formed recently after splintering from Al-Qaeda in the Islamic Maghreb (AQIM), which experts say has raked in some $120 million (93 million euros) in ransom payments in the past eight years.
Before the video was released, Gourdel's family expressed hope for his freedom and spoke of their anguish.
"We learned with great pain of the kidnapping of Herve Gourdel, our father, our partner, our son, our brother and our very dear friend," said a family statement sent to AFP Tuesday.