French investigators have handed preliminary terrorism charges to the brother-in-law of one of the Islamic extremists who attacked the French satirical newspaper Charlie Hebdo last year.

Mourad Hamyd, 20, was arrested on a French warrant in Bulgaria last month on suspicion he was trying to travel to Syria to join the Islamic State group. He has denied the allegations.

The Paris prosecutor's office said Saturday that he was given preliminary charges of association with terrorist criminals.

Hamyd is the brother-in-law of Cherif Kouachi, one of two brothers who attacked Charlie Hebdo's Paris office in January 2015, killing 12 and shocking France.

A high school student at the time, Hamyd was briefly detained on suspicion of having a role in the attack, but classmates said he was in school.