Anti-terror campaign must be 'stepped up', Hollande tells UN

French Defense Minister Jean-Yves Le Drian said on Thursday that Algerian forces are hunting for those who beheaded French mountaineer Herve Gourdel after France's airstrikes on Islamic State extremists.

He also said France, which has limited its airstrikes so far to Iraq, would continue to evaluate whether to extend them to Syria, as the United States has done to thwart IS advances. He said French jets were in flight as he spoke.

Gourdel, 55, was seized on Sunday while hiking in the Djura Djura mountains of northern Algeria by a group linked to IS, "Soldiers of the Caliphate". His Algerian companions were freed.

Video of his beheading was posted online, and authorities confirmed its authenticity before it was removed.

The Algerian government condemned Gourdel's murder as "heinous" and "despicable", and the nation's armed forces vowed to continue fighting terrorism until it is eradicated.

More than 1,500 troops, including paratroopers, were deployed to search for Gourdel and track down his abductors in the Djurdjura mountains, where the presence of extremist groups linked to al-Qaida persists despite steady efforts to eliminate them.

The Kabylie region, where Gourdel was kidnapped, is known to be plagued by abductions, but the victims have been mostly locals. In the majority of cases, hostages were set free after a ransom was paid.

French President Francois Hollande was to convene an emergency meeting of his defense council on Thursday with renewed determination to fight IS extremists after the "cowardly" beheading of Gourdel.

Hollande vowed the country would "never give in to blackmail" after the militants demanded an end to French military operations in Iraq.

"The fight against terrorism must continue and be stepped up," he told the United Nations General Assembly.

US President Barack Obama said: "We stand with you and the French people as you grieve this terrible loss and as you stand up against terror in defense of liberty".

Hometown mourns

Emotions ran high in Gourdel's hometown of Nice after news of the murder broke, with flags in the city flying at half-mast.

The deputy mayor of the French Riviera resort, Christian Estrosi, visibly moved, told reporters after meeting Gourdel's relatives on Wednesday that the country had been plunged into "national mourning".

"It's a terrible shock" for the parents, he said, adding that the family had reacted to Gourdel's death "with dignity, anger and an unspeakable pain".

Further north, in Saint-Martin-Vesubie's Mercantour national park, where Gourdel worked as a guide, mayor Henri Guige said he was "shocked".

"For me, this is a war in which they are attacking civilians, the innocent," Guige said.

A passionate photographer and mountaineer, Gourdel liked going off the beaten track, though he was always careful, acquaintances said.

Close friend Laurent Geny described him as someone who was "profoundly good, very humane and who loves the Maghreb culture".

AP - Xinhua - AFP