French police on Wednesday arrested a 15-year old suspected of planning an attack and using encrypted social media channels to communicate with a French Islamist militant believed to be in Syria or Iraq, sources said.
In an operation led by France's domestic intelligence agency, police swooped on the teenager in Paris' eastern 20th arrondissement.
Interior Minister Bernard Cazeneuve confirmed the operation. "We're working with extreme intensity to identify those we think are likely to carry out an attack," he told reporters, adding that Islamic State was recruiting "younger and younger individuals".
It is the second time a 15-year-old minor suspected of plotting to kill in the name of Islamic State has been arrested in five days. A source inside the prosecutor's office said both youngsters had used Telegram to communicate with Rachid Kassim, an Islamic State jihadist of French nationality.
Their arrests follow the detention of three women, including a 19-year-old, who had allegedly wanted to attack a Paris railway station using a car laden with gas cylinders.
France is reeling from a wave of militant attacks on its territory that have killed more than 230 people since January, 2015, and its intelligence services are struggling to dismantle a web of militant networks inside the country.
The attacks have varied in style and profile of killer: In November last year, a squad of suicide bombers and gunmen killed 130 people in a sophisticated and coordinated attack on multiple sites in Paris; In July, a Tunisian delivery man killed 86 people when he drove his truck through a crowd on Nice's seafront; and two militants knifed to death an elderly priest at his altar in a church in northern France.
"What sets France apart (from other European nations) is the wide-open profile of recruit: urban or rural, Muslim or convert, man or woman," said Arnaud Danjean, a European Parliament lawmaker who specialises in defense and security.
"Acts like the attempted attack with gas cylinders, the throat-slitting of a priest, or the guy who ploughs his truck through a crowd, that today is the face of this threat" in France, said Danjean.