France says it is not spooked by a call for Muslims to kill citizens of countries fighting the Islamic State group, hours before jihadists claimed the kidnapping of a Frenchman in Algeria.
"France is not afraid," Interior Minister Bernard Cazeneuve said repeatedly during a televised statement on Monday, after IS circulated grisly tips for its followers on how to kill "disbelievers".
The Algerian group Jund al-Khilifa, which has pledged allegiance to IS, said in a video that they would kill French national Herve Pierre Gourdel, who was abducted in a mountainous region of northeastern Algeria on Sunday, unless Paris halts air strikes on the extremists in Iraq.
In the video, the kidnappers said they were responding to the IS appeal to kill citizens of countries who have joined the coalition against them.
French President Francois Hollande spoke with Algerian Prime Minister Abdelmalek Sellal on Monday and said both countries were working together to free the Frenchman.
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Earlier Cazeneuve had defied an explicit threat against what IS labelled "the spiteful and filthy French", saying it was "not the first time France has been threatened by terrorist groups".
Paris did however urge nationals abroad to exercise "utmost caution" after the threat.
The menace posed by the Islamic State group that has seized large areas of Iraq and Syria has seen anti-terror laws rewritten, security boosted and raids carried out against homegrown jihadist groups from Europe to Australia.
Authorities are fearful that returning jihadists will launch attacks at home, like French citizen Mehdi Nemmouche, who is suspected of killing four people in an attack on the Jewish Museum in Brussels in May.
France has Europe's largest Muslim population, and 930 of its citizens have joined the fighting in Syria and Iraq, according to official figures.
French deputies voted last week on a new counter terrorism law aimed at halting the flow of would-be jihadis to the war-torn region.
"The question on everyone's lips is not when there will be an attack, but where," said a French intelligence source.
The UN Security Council will on Wednesday discuss a resolution that would oblige nations to prosecute those who travel to fight with jihadist groups or fund them.
President Barack Obama will preside over the efforts to boost international co-operation in the fight against IS, which has seen the US and France carry out air strikes against the group.
Australia is also deploying fighter jets to join the campaign.
Meanwhile the UK and Australia were drawing up tougher laws of their own. Britain, which has raised its terror risk level to "severe", is planning measures that will allow police to temporarily strip departing suspects of passports at the border.
