French authorities fearing an attack arrested and charged a 26-year-old man ahead of the Olympic torch relay procession in Bordeaux on Thursday, officials said.

"An individual planning a violent act during the Olympic torch relay in Bordeaux has been questioned," Interior Minister Gerald Darmanin said on X, the former Twitter.

An investigation into the individual, identified as Alex G., opened after alerts to France's online extremism watchdog detected posts referring to a 2014 mass killing in California. 

The man, 26, who was arrested on Tuesday, appeared before an investigating magistrate on Thursday. He was charged with criminal conspiracy but released ahead of trial, while placed under judicial control.

Prosecutors - who had asked that the man was remanded in custody - said that they would appeal the decision.

The Olympic torch went through the southwestern city as part of a nationwide tour ahead of the Olympics that open on July 26. Bordeaux will host several football matches in the Olympic tournament. 

The whole relay is surrounded by strict security.

The prosecutor recommended Alex G. be remanded in custody after he admitted to considering carrying out an attack, sources said. 

"No reference was made to the Olympic torch," Bordeaux prosecutor Frederique Porterie said in a press statement. 

According to a police source, Alex G. shared a video clip featuring Elliot Rodger, who killed six people and himself in a 2014 rampage in California, writing, "we miss you, Elliot".

Police seized "a revolver, a rubber bullet gun, several cell phones, and a computer" during a search of the suspect's house in a Bordeaux suburb.

The prosecutor said people close to the suspect say he is "psychologically very fragile. However, the appointed psychiatrist has not revealed any particular disorder".

Initial investigations showed an interest in the incel movement, an online group of women-hating men who describe themselves as "involuntarily celibate", Porterie added.