Seven people with links to terrorist networks, at least three of whom were planning attacks, have been arrested in France this month, Interior Minister Bernard Cazeneuve said Tuesday.

Cazeneuve said at a press conference that French police had arrested as many people for terror links in the first half of 2016 as for the whole of last year.

He gave no details of the latest arrests, however.

On August 8, a 16-year-old girl from the Paris suburb of Melun was remanded in custody on charges of planning a jihadist attack.

The teenager was an administrator of a group on Telegram, an encrypted messaging app that was used by two jihadists to plan the murder of a priest in Normandy in July.

According to investigators, she "relayed numerous Islamic State group propaganda messages calling for attacks" and also expressed a personal desire to "take action".

Cazeneuve and his German counterpart Thomas de Maiziere on Tuesday asked the European Commission to consider legal measures that could be taken against the operators of encrypted messaging services such as Telegram.

After a meeting between the two ministers, Cazeneuve said such legislation could "impose obligations on operators who show themselves to be non-cooperative, in particular when it comes to withdrawing illegal content or decrypting messages as part of an investigation."

Meanwhile a 19-year-old from the Riviera city of Nice -- who was born to a family of Jehovah's Witnesses but converted to Islam -- was on Tuesday sentenced to three years in prison for glorifying terrorism.

He was sentenced for his regular visits to jihadist sites on which he posted "nauseating" comments and photos, said a source close to the investigation.

French security services are scrambling to prevent further violence after two attacks in July that shocked the country just as it was starting to rebound from the jihadist bloodshed in Paris in November.

On July 14, a 31-year-old Tunisian rammed a 19-tonne truck into crowds of people celebrating Bastille Day in the Riviera city of Nice, killing 86 people and wounding more than 400.

And on July 26, two 19-year-olds stormed a church in the northern town of Saint-Etienne-du-Rouvray and slit the throat of an elderly priest.

Several major cultural and sporting events were cancelled in the wake of the attacks on security grounds.