Hundreds of protesters defied a ban on Saturday to march in central Paris against police violence, a week after riots sparked by the killing of a teenager in a Parisian suburb.

Police dispersed the crowd from Paris’s huge Place de la Republique, sending several hundred people towards the wide Boulevard Magenta, where they were seen marching peacefully.

The Paris police department said in a decision published on its website that it had banned the planned demonstration, citing a “context of tensions”.

“We still enjoy freedom of expression in France, but freedom of assembly, in particular, is under threat,” said Felix Bouvarel, a health worker who came to the gathering in spite of the ban which he called “shocking”.

Authorities also banned a demonstration in the northern city of Lille on Saturday, while a march in Marseille took place with a changed trajectory, ordered out of the city centre.

Interior Minister Gerald Darmanin said this week that more than 3,000 people, mostly teenagers, had been arrested in six nights of riots that ended a week ago. Some 2,500 buildings were damaged.

The riots were triggered by the June 27 fatal shooting by a police officer of 17-year-old Nahel M at a traffic stop. A police officer is under investigation for voluntary homicide; his lawyer says he did not intend to kill the teen.

Saturday’s demonstration was called by the family of Adama Traore, a Black Frenchman whose death in police custody in 2016 has been marked by annual protests since. Organisers had sought to move it to central Paris after it was banned in Beaumont-sur-Oise, the Paris suburb where Traore died.

French authorities and politicians, including President Emmanuel Macron, have denied institutional racism within the country’s law enforcement agencies.

The French foreign ministry denied on Saturday that the country’s legal system is racist, a day after the United Nations Committee on the Elimination of Racial Discrimination (CERD) called for France to address “the structural and systemic causes of racial discrimination, including in law enforcement”.

“Any accusation of systemic racism or discrimination by law enforcement in France is unfounded,” the foreign ministry said.