A 16-year-old girl is among four people arrested for allegedly planning a new terror attack in France.
The teenager was arrested alongside her 20-year-old boyfriend and two other men aged 26 and 33 in Montpellier on Friday morning.
Local reports said the group were suspected of planning a suicide bombing in an unspecified "tourist area" of Paris.
Explosives and other equipment were reportedly found during searches, sources told Info M6.
Police discovered 71g of triacetone triperoxide (TATP), a powerful explosive widely used by Isis militants, inside a makeshift factory manufacturing the substance, BFMTV reported.
The volatile explosive, known as the “mother of Satan”, was used in the Paris and Brussels attacks, as well as the 2005 London bombings.
Isis propaganda magazines have contained instructions on how to make TATP, which is difficult to detect, from legally available and low cost products.
All four suspects were under surveillance by French authorities and were suspected of preparing a "violent action", while the 20-year-old man is suspected of wanting to commit a suicide bombing.
They were arrested after buying acetone, one of the key ingredients of TATP, while the girl had allegedly expressed her desire to either journey to Syria or Iraq, or attack France, on social networks.
The arrests came a week after a suspected Isis supporter attacked French soldiers guarding Le Louvre.
Abdallah el-Hamahmy, a 29-year-old Egyptian man, claimed he received no direct orders from the terrorist group and intended to deface artworks.
France has been repeatedly targeted by Isis, whose militants launched a series of mass shootings and suicide bombings across Paris that killed 130 people in November 2015.
A supporter killed 86 people by ramming a lorry into crowds celebrating Bastille Day in Nice in July, and supporters have also carried out several stabbing attacks including the murder of a police officer and Catholic priest.
The country remains under a continuing state of emergency, which has been extended four times, prompting human rights concerns from the United Nations.
France's top constitutional court has struck down a contentious law brought in under the emergency measures, which allowed prison sentences for the offence of consulting “terrorist websites”, saying it infringed on the ability to communicate freely.
The 2016 law, approved after the attacks in Paris, was intended to stem the influence of jihadi social networks and online propaganda and made exceptions for purposes of research or informing the public.
In a ruling on Friday, judges said France had other laws at its disposal to protect the public from acts of terrorism and imprison Isis sympathisers.
