The girls, aged 15 and 17, were arrested on Wednesday and were presented to an anti-terrorism judge on Friday.

The police said they exchanged messages on Facebook in which they said they wanted to attack a Paris concert hall, similar to the "Islamic State" assault on the Bataclan concert hall four months ago.

The November 13 terrorist attacks in Paris killed 130 people - 90 at a rock concert at the Bataclan - and forced French authorities to declare a state of emergency.

The girls were charged with criminal conspiracy linked with a terrorism plot.

Two other girls who took part in the Facebook conversation were interrogated by the police but were later released without charges.

Authorities said the girls' project appears to have been at an initial stage and "neither weapons nor explosive substances have been discovered."

The 15-year-old girl would remain in police custody, whereas the older one would be released under judicial supervision, officials said. The authorities have not revealed details about their identities.

shs/ rc (AP, AFP)