Thousands of demonstrators across France took part in protests on Sunday to support freedom of speech and to pay tribute to a French teacher who was beheaded outside a school near Paris after discussing caricatures of Islam's Prophet Muhammad in class.

Political leaders, associations and unions demonstrated on the Place de la Republique in central Paris. Protesters also gathered in other major French cities, including Lyon, Toulouse, Strasbourg, Nantes, Marseille, Lille and Bordeaux.

"You do not scare us. We are not afraid. You will not divide us. We are France!" tweeted Prime Minister Jean Castex, who was among those gathered in Paris.

History teacher Samuel Paty was decapitated on Friday by an 18-year-old Moscow-born Chechen refugee who was shot dead by police.

The teacher had been the target of online threats for showing the cartoons in class, with the father of one schoolgirl launching an online call for "mobilization" against him, France's anti-terror prosecutor Jean-Francois Ricard said.

Witnesses said the young man, named as Abdullakh A., was spotted at the school on Friday afternoon asking pupils where he could find Paty.

On Saturday, hundreds of pupils, teachers and parents flooded to Paty's school to lay white roses.

Charlie Hebdo editors urge demo

The editors of the satirical magazine Charlie Hebdo called for the demonstration in Paris on Sunday afternoon together with the organization SOS Racisme and teachers' unions.

"It is absolutely important to show our mobilization and our solidarity, our national cohesion," Education Minister Jean-Michel Blanquer told France 2 television, calling on "everyone [to] support the teachers."

The solidarity rallies came as French authorities say they have detained an 11th person following the atrocity, including four family members of the attacker, who had been granted a 10-year residency in France as a refugee in March.

The Paris prosecutor said a text claiming responsibility and a photograph of the victim were found on the suspect's phone.

He also confirmed that a Twitter account belonging to the suspect posted a photo of the victim's body minutes after the attack. The message in the Tweet indicated the attack was motivated by the teacher showing caricatures of Muhammad in class.

Read more: Coronavirus digest: France reports over 32,000 new infections

'Je suis prof'

Many demonstrators in Paris on Sunday held signs which used the slogan "Je suis prof" (I am a teacher) or "Je suis Saumel" (I am Samuel), echoing "Je suis Charlie" that became the rallying cry of solidarity marches in 2015 following the deadly attack on the offices of the satirical magazine.

A subsequent series of attacks in France, many claimed by the "Islamic State" (IS) armed group, cost more than 230 lives in 2015 and 2016.

Read more: Tunisian MP probed for allegedly glorifying beheading of French teacher

Suspects accused of links to the Charlie Hebdo attacks are currently before the courts in a trial that is expected to run until mid-November.

Charlie Hebdo's former office was the site of a cleaver attack just a few weeks ago after it republished some of the cartoons of Muhammad ahead of the ongoing trial.

mm,dv/rs (AFP, AP, dpa)