He is the third French 15-year-old in just five days to have been remanded in custody and placed under formal investigation for terrorism.
The arrests follow calls by the Islamic State (IS) group to attack soft targets in the West.
The boy, described as an A-grade student who denounced the November 13 terror attacks in Paris which left 130 people dead, was arrested Wednesday and remanded in custody on Friday over his links to a terrorist network. According to the source, the teen had been in touch with Rachid Kassim – a French member of the Islamic State (IS) group who is wanted by the police – via the encrypted message forum Telegram.
The teen expressed his willingness to carry out a terrorist atrocity to Kassim.