A French national has been kidnapped in eastern Algeria on Sunday, France's foreign ministry said.
The kidnappers also issued a video threatening to kill him if Paris did not halt its intervention in Iraq, Reuters reported.
In the video, the kidnapped person identified himself as Herve Gourdel, 55, from Nice in southern France.
The Caliphate Soldiers, a group linked to Islamic State militants, published a video on the Internet soon after the French ministry's announcement on Monday, claiming responsibility for the kidnapping.
The French foreign ministry later confirmed the video was authentic.
In New York, French Foreign Minister Laurent Fabius said the taking of a French hostage would not deter French participation in a US-led coalition of nations against Islamist State militants.
"We will do everything we can to liberate hostages," Fabius, in New York for UN General Assembly, told reporters. "But a terrorist group cannot change France's position."
The kidnapping came just hours after Islamic State spokesman Abu Muhammad al-Adnani urged the group's followers to attack citizens of the United States, France and other countries which have joined a coalition to destroy the radical group.
