France's interior minister says authorities have foiled a plot by four would-be extremists to attack military bases.

Interior Minister Bernard Cazeneuve said Wednesday that four suspects aged between 16 and 23 were arrested Monday at four separate locations around France.

Cazeneuve said the group's leader had been under surveillance after his online activities raised investigators' suspicions.

The minister said authorities break up similar plots every week in France, where more than 300 people have been implicated in jihadi activities since 2012.