Three people have been arrested in France on suspicion of plotting a terrorism attack, police sources say.
A bomb disposal squad was called in to sweep the home of one of the suspects, in the central city of Clermont-Ferrand, French media say.
The other two arrests were reportedly in Marseille and in the Paris region.
France is on high alert after a series of deadly attacks in recent years by militants claiming to be from the Islamic State group.
Few details of Tuesday's arrests are yet known.
One source told Reuters news agency that the suspects were arrested "as part of a preliminary investigation started in January on suspicion of leaving for Syria or committing an act in France".
Another police source quoted in Le Monde said the plot was sufficiently advanced that the French intelligence agency, the DGSI, decided to intervene.
Since the beginning of 2015, at least 230 people have been killed in jihadist attacks in France.
On 10 February, four suspects were arrested in Montpellier preventing what Interior Minister Bruno Le Roux said was an "imminent" terror attack on French soil.
Three men and a girl of 16 were found with bomb-making materials by anti-terrorist police in a raid on a flat in the southern city.
The week before a soldier received minor injuries when a machete-wielding man tried to enter the Louvre museum in Paris.
The man, a 29-year-old Egyptian named Abdullah Hamamy, was shot and critically injured.