Police officers taking part in a mock terror attack in Lille on Thursday as part of the security measures set for the upcoming Euro 2016 football championship in France.
The French government is seeking a new extension of a state of emergency to cover Europe's premier football tournament in the summer.
The measure to boost security powers, imposed following the Nov 13 terrorist attacks that left 130 people dead in the French capital, was extended by three months in February until May 26.
The emergency policing powers allow the Interior Ministry to place under house arrest any person whose behaviour is considered "a threat to security and public order" and to order searches of homes at any hour without involving a court.
The Euro 2016 tournament will run from June 10 to July 10. Organisers say some two million visitors are expected during Euro 2016, in which 24 national teams will compete.
The authorities have launched a series of exercises to prepare for possible attacks during the tournament, which will see matches in several big cities including Bordeaux, Lille and Marseille besides the flagship Stade de France in Paris.
Human rights activists slammed the government move to extend the emergency measure, prompting Prime Minister Manuel Valls to say that it "cannot be a permanent state".
"But for these major events... we need to have these powers, these possibilities, under the control of a judge, under the control of Parliament, to allow for the best response in the face of terrorism," he said on French radio.