PARIS A French-Moroccan man with suspected links to Islamic State was placed under formal investigation on Sunday on suspicion of planning to carry out "violent acts", the Paris prosecutor's office said.
French anti-terrorism police arrested Youssef Ettajouar, 28, and three others on March 16 after opening a preliminary investigation on the basis that they were ready to take action.
At the time, Interior Minister Bernard Cazeneuve said investigators were focusing on one of the suspects, adding that he was thought to have ties with Islamic State in Syria.
The three others were released on Sunday, but Ettajouar, who was sentenced to five years in prison for having wanted to go to Syria in 2012, was remanded in custody.
"The exact nature of the plans has not been established at this stage, but there are a certain number of elements that indicate his intentions," an official at the prosecutor's office said.
He will be investigated for charges of criminal association related to a terrorist enterprise as well as violating his house arrest.
Under French law, this step means "serious or consistent evidence" points to probable implication of a suspect in a crime. It is a step toward a trial, but a number of such investigations have been dropped without trial.
During the arrests on Wednesday, police seized an unused automatic rifle cartridge and computer equipment, French television network TF1 said on its website. No weapons were found, a source close to the investigation told Reuters.
The investigation was focused in particular on Ettajouar, who had been under house arrest since Feb. 29 under state of emergency measures in effect in France since Islamist militants killed 130 people in a series of attacks in Paris last November.
He was sentenced to five years in prison in March 2014 after being arrested two years earlier when he tried to leave France for Syria, but was released in October 2015.
(Reporting By Emmanuel Jarry and John Irish; Editing by Tom Heneghan)