A teenage girl is reported to be among those arrested in Montpellier
Four people, including a 16-year-old girl, have been arrested on suspicion of planning an attack in Paris.
French prosecutors say the four were arrested in Montpellier in the south of the country.
They were allegedly planning to detonate an explosive belt in a tourist area of the capital.
Explosives and computer equipment were discovered in a makeshift laboratory at the suspects' homes, according to the Paris prosecutor's office.
It said around 70 grams of the explosive TATP were found.
It is the same explosive used in the 2015 attack on Paris and the March 2016 attack in Brussels.
France has been targeted in a number of terror attacks, leading to a state of emergency being declared until after the Presidential elections in July.
A number of attackers in Paris killed 130 people and critically injured another 100 in November 2015.
In July 2016 a 19-tonne truck was driven through a Nice tourist area, killing 86 people.
Radical Islamists were blamed for the attacks.
A two-and-a-half metre high glass security barrier is to be constructed around the Eiffel Tower because of the fear of terror attacks.