A French man has been kidnapped in Algeria by a militant group linked to Islamic State (IS), French Foreign Minister Laurent Fabius has confirmed.
Herve Gourdel was seized on Sunday in the unsettled north-east Kabylie area.
Mr Fabius said an online video that showed Mr Gourdel flanked by armed men, calling on France not to strike IS militants in Iraq, appeared authentic.
He said France would do everything it could to liberate Mr Gourdel, but that the situation was “extremely critical.”
Earlier, Islamic State militants warned they would target France – and other countries – after French jets launched air strikes in Iraq against the group.
IS jihadists have seized large swathes of territory in eastern Syria and across northern and western Iraq, forcing tens of thousands of people to flee their homes this year.
France’s foreign ministry said in a statement: “We confirm the authenticity of the video showing images of French hostage Herve Gourdel, kidnapped in Algeria in the region of Tizi Ozou on Sunday.”
“The threats made by this terrorist group shows once again the extreme cruelty of [Islamic State] and those who say they are affiliated to it.”
Speaking in New York, where he is attending the UN General Assembly, Mr Fabius told reporters: “We will do everything we can to liberate hostages… but a terrorist group cannot change France’s position.”
The video shows Mr Gourdel flanked by two masked men.
The militants say they are members of the Algerian group Jund al-Khilifa, also known as Soldiers of the Caliphate.
The group has pledged allegiance to IS. Some reports have also described it as an al-Qaeda splinter group.
The militants said that they were responding to a call from IS to attack citizens of countries taking part in strikes in Iraq.
The apparent kidnappers threatened to kill Mr Gourdel unless France ended its military operation.
‘Everything being done’
In the video, Mr Gourdel identified himself as a 55-year-old from Nice, southern France.
Speaking apparently under duress, he said: “This armed group is asking me to ask you [French President Francois Hollande] to not intervene in Iraq.”
French newspaper Le Monde described Mr Gourdel as a mountain guide and photographer in Algeria as a tourist.
The Algerian interior ministry said he and two Algerian companions had been driving through mountains near the village of Ait Ouabane, when they were stopped by armed men.
The gunmen let the Algerians go but seized the Frenchman.
In Paris, President Hollande’s office said he had spoken by telephone to Algerian Prime Minister Abdelmalek Sellal.
A statement said there was “total co-operation” to try to find the Frenchman and that authorities in both countries were in constant contact.
“Everything is being done to find our fellow countryman. Authorities are mobilised and no hypothesis is being discarded,” the French government added.
Kabylie is a rugged, mountainous region which has seen several kidnappings of Algerian businessmen for extortion.
Most of those who were abducted were later freed by security forces.
Al-Qaeda’s North Africa branch, Al-Qaeda in the Islamic Maghreb (AQIM), and other militant groups are known to operate in Algeria.
AQIM has carried out deadly attacks in Kabylie this year.
France on Monday raised the threat level for 30 of its embassies throughout the Middle East and Africa after beginning its first air strikes against IS targets in Iraq on Friday.
It has said that everything must be done to remove IS militants from the region.