A tribute to Quentin Deranque in Paris on Feb. 15.Alain Jocard / AFP via Getty Images

Eleven people including an aide to a far-left lawmaker were arrested in France overnight and early on Wednesday on suspicion of involvement in the killing of a far-right activist.

Shortly after the announcement, the Paris headquarters of the hard-left France Unbowed (LFI) party received a bomb threat and had to be evacuated until the all-clear was given when police secured the scene.

Far-right activist Quentin Deranque, 23, died on Saturday after being beaten by hard-left activists outside a conference centre in Lyon where Rima Hassan, an LFI member of the European Parliament, was speaking.

Videos of the confrontation were widely shared on social media. Hassan and other members of the LFI have condemned the killing.

The Lyon prosecutors` office, which has opened a murder investigation, said 11 suspects have been detained so far. Among them is an aide to LFI lawmaker Raphael Arnault, who said on Tuesday that the aide had "stopped all parliamentary work".

"It is now up to the investigation to determine responsibility," Arnault said on X.

Both the hard left and hard right have been capitalising on frustration with the minority centrist government ahead of local elections next month and a presidential vote next year, set to take place in a highly polarised environment.

Speaking to reporters on Wednesday, the LFI`s national coordinator Manuel Bompard said his party was in no way responsible for Deranque`s death, and that it now felt threatened itself.

Jordan Bardella, party president of the far-right National Rally, has accused LFI leader Jean-Luc Mélenchon of opening the "doors of the National Assembly to presumed murderers".