French prosecutors have charged a 17-year-old over graphic threats sent to more than 150 schools in recent weeks, a judicial source said Saturday.

Some of the messages, sent via the dedicated messaging systems for teachers and students, included links to videos of beheadings and other violence, said the source.

The young man was detained on Thursday in the Malakoff suburb south of Paris. Prosecutor Laure Beccuau had said he did not have any criminal record for this kind of behaviour.

After questioning he was charged with a range of crimes including death threats, promoting terrorism and hacking personal data. He has been placed in pre-trial detention.

The messages were sent via the ENT digital platform that serves as a link between teachers, pupils and parents, internal emails, or the Pronote software used by the education ministry.

One school in the Val-d'Oise department northwest of the capital received a message "threatening a terrorist attack". It included "links to a video showing people being decapitated", said a police source.

In the Seine-et-Marne department east of Paris, a secondary school received a message saying explosives had been hidden throughout the establishment.

School officials and teachers have been on high alert since 2020, when Samuel Paty, a 47-year-old history and geography teacher, was stabbed and then beheaded by a radicalised Islamist near his secondary school near Paris.

In October, a radicalised Islamist stabbed a former teacher to death in the northern town of Arras.

And in the autumn of 2023, a flurry of false bomb alerts targeted schools as well as airports and tourist sites.

Education Minister Nicole Belloubet said Thursday that the ENT messaging function had been suspended while the investigation continued.

She also announced the creation of a rapid-response force for schools facing such threats.