Fifth suspect arrested in foiled French attack plot

French police arrested a 16-year-old in the eastern city of Strasbourg on Tuesday as part of an investigation into a suspected plot to attack security forces and possibly the presidential Elysee Palace, a judicial source told AFP.

His arrest comes after three adults and another teenager were arrested on April 26 over plans to carry out what Interior Minister Christophe Castaner said would have been an "extremely violent terror attack".

The attack was allegedly planned to coincide with the start of the Muslim holy month of Ramadan, which began in France on Monday, with officials saying the suspects had scouted out areas near the Elysee and a police station in the Parisian suburb of Aulnay-sous-Bois.

France's TF1 television said the fifth suspect was a high school student of Chechen origin who was arrested at his parents' home.

"Intelligence services suspect he was supposed to publish a video claiming allegiance to Daesh on the group's behalf," TF1 reported, using an Arabic acronym for the Islamic State group, a claim confirmed by the judicial source.

"Several projects were envisioned, all against security forces," including those stationed outside the Elysee, the source said.

Of the four arrested initially, one is a 17-year-old who served a year in prison after being convicted of trying to join jihadist fighters in Syria in 2017.

The three others, aged 26, 38 and 39, were previously known to police only for petty crimes.

France remains on high alert since a wave of domestic jihadist attacks since 2015 which have killed more than 250 people.

At the end of March, two men were indicted in Paris on suspicion of planning an attack on a school or a police officer.