The French government has raised its terrorist alert to the highest level after the deadly attack on a Russian concert hall and the claim by Islamic State it was responsible.
French Prime Minister Gabriel Attal announced the move on Sunday (Monday AEDT) three months before Paris hosts the Olympic Games.
In a post on the social media site X, formerly known as Twitter, he said the decision was taken "in light of the Islamic State's claiming responsibility for the (Moscow) attack and the threats weighing on our country".
Earlier, French President Emanuel Macron held an emergency security meeting in the wake of the Moscow massacre that killed at least 130, local media reports.
The Islamic State group claimed responsibility for the attack in a statement posted on affiliated social media channels, although the Kremlin insists Ukraine played a part. Kyiv insists it had no role.
In a statement posted by its Aamaq news agency, the Islamic State's affiliate in Afghanistan said it had attacked a large gathering of "Christians" in Krasnogorsk.
France's terror alert system has three levels and the highest is sounded in the wake of an attack in France or abroad or when a threat of one is considered to be imminent.
Moscow terror attack suspects appear in court
It can trigger beefed-up security protocols such as intensified patrols by armed troops in public places such as airports, train stations and places of worship.
Jihadist terrorist groups have regularly targeted France for attacks, including the Bataclan concert hall massacre in Paris in 2015.
Ahead of the Olympic Games and Paralympics starting in July, expected to attract millions of visitors, the country has been on high alert.
