French authorities on Tuesday arrested nine suspects over the killing last week of a far-right activist, including an assistant to a hard-left member of parliament, a prosecutor and an informed source said.

Quentin Deranque, 23, died after sustaining a severe brain injury when he was attacked by at least six people last week on the sidelines of a far-right protest against a left-wing politician speaking at a university in the southeastern city of Lyon.

The incident has fuelled tension between France’s far right and hard left ahead of municipal elections in March and the 2027 presidential race, in which the far-right National Rally (RN) party is seen as having its best chance yet of winning the top job.

Lyon prosecutor Thierry Dran announced the arrests of four suspects, then shortly afterwards that of five others, bringing the total to nine.

A source following the case, speaking on condition of anonymity, said an assistant to Raphael Arnault, a member of parliament from the hard-left France Unbowed (LFI) party, was among the first four detained.

Arnault reacted by saying he was firing the assistant.

The head of the LFI, Jean-Luc Melenchon said that those who had attacked Deranque had “dishonoured” themselves by acting with apparent lethal intent.

“When it comes to violence, whether it be defensive or offensive… not all blows are allowed,” he said.

An anti-immigration collective called Nemesis, which claims to fight violence against Western women, said Deranque had been at the protest in Lyon to protect its members.

Nemesis has blamed the killing on La Jeune Garde (Young Guard), an anti-fascist youth group co-founded by Arnault before he was elected to parliament.

La Jeune Garde — which was dissolved in June — has denied any links to the “tragic events”, while Arnault has called the killing horrific.

On Monday, parliament speaker Yael Braun-Pivet said one of Arnault’s assistants had been banned from the chamber after being mentioned by witnesses.