Authorities say one of those arrested could have been planning "violent acts"
French anti-terror police have arrested four suspected jihadists, including one who could have been planning "violent acts", say authorities.
Interior minister Bernard Cazeneuve said the man was thought to have ties with Islamic State in Syria.
It comes after media reports that the four were thought to have been plotting to carry out an imminent attack in Paris.
But Mr Cazeneuve warned against jumping to that conclusion as checks were under way.
He said: "We have information about one person that suggests that he could undertake violent actions in France."
He added: "This person was arrested this morning along with people linked with him."
Three men and a women were detained, according to TV station TF1, which claimed security forces had files on them for their Islamist ties.
It said the arrests took place at dawn in Paris and the nearby northern suburb of Seine-Saint-Denis.
And during a search on Wednesday morning, investigators found an unused cartridge for an assault rifle, electronic material, USB computer sticks and a safe.
It was claimed the inquiry was focused in particular on a 28-year-old Frenchman who had been under house arrest since 29 February.
According to reports, the French citizen was sentenced to five years in prison in March 2014 after he was arrested two years earlier when he tried to leave France for Syria.
He was released in October 2015.
His partner was also arrested along with two French brothers of Turkish origin, it was claimed.
France is already on heightened alert following last November's attacks in the capital in which 130 people were killed.
One of the 2015 attacks took place at the Stade de France stadium in Seine-Saint-Denis.
On Tuesday, a man was shot dead during an anti-terror raid in Brussels, Belgium, linked to the investigation into the deadly shootings and bombings last year.
Belkaid Mohamed, a 35-year-old Algerian who was in Belgium illegally, was killed by police snipers.
He was found with an Islamic State flag, an assault rifle and a book of Salafist literature beside his body, according to Belgian prosecutors.
Four police officers were injured in the shootout, which began after Belgian and French authorities carried out a routine search of a property.