French Interior Minister Gérald Darmanin said Monday that an "ultra-left activist" has been arrested after allegedly breaking into a railway site, as a national investigation continues into last week’s arson attacks on train networks that reportedly disrupted travel for nearly a million passengers in France hours before the 2024 Paris Olympics opening ceremony. 

In a post on X, Darmanin said the suspect was arrested on Sunday at a railway site in the Seine-Maritime region of western France

The post cited the "sabotage" of the network of France’s national railway company, SNCF, that happened overnight Thursday into Friday before the opening of the Paris Olympics. The Paris prosecutor's office, however, said the unidentified man taken into custody at an SNCF site near the city of Rouen on Sunday could not immediately be linked to the widespread arson attacks at this time, The Associated Press reported. 

The interior minister shared a report by the French daily morning newspaper Le Figaro in announcing the arrest. A police source who spoke to Agence France-Presse revealed an "activist from the far-left movement" was taken into custody on Sunday at an SNCF site in Oissel (Seine-Maritime), according to the newspaper. 

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Soldiers outside Paris Olympics

Soldiers patrol outside Gare du Nord train station at the Summer Olympics, Friday, July 26, 2024, in Paris. (AP Photo/Mark Baker)

In the man’s vehicle, authorities found "access keys to SNCF technical premises," "cutting pliers," a "set of universal keys," and literature related to the far left, including a copy of Romain Huët's book "Le vertige de l'riot: de la Zad aux Gilets jaunes," the source reportedly added. 

A train conductor was said to have witnessed several individuals near a "railway electrical cabinet" just south of Rouen on Sunday. As the conductor passed by, the group fled the area that is not open to the public, the New York Times reported, citing a statement from the Rouen prosecutor's office. Authorities detained the man for questioning when he returned to retrieve his vehicle left at the scene. 

Speaking to France 2, Darmanin said the "acts of sabotage" last week were carried out in a voluntary, very precise manner and demonstrated "the traditional mode of action of the ultra-left."

"The question is whether they were manipulated or is it for their own benefit," Darmanin said. "What has really interested and worried us is that these are extremely specific locations used for communication," he added, according to the New York Times. "Clearly, it was extremely well-targeted, it was not done randomly."

Le Figaro reported that fiber optic cables running near the tracks intended to transmit safety information to drivers, including red light signals, were cut and set on fire at various locations on the TGV line network overnight Thursday to Friday in what one source close to the investigation described as a "well-prepared" operation organized by the "same structure." 

French police inside a train station

Police officers patrol inside the Gare du Nord train station, Friday, July 26, 2024, in Paris. (AP Photo/Mark Baker, File)

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With the national investigation still underway, train traffic had largely resumed by Monday.

Meanwhile, the French government said multiple telecommunications lines were hit by acts of vandalism again overnight Sunday into Monday, impacting fiber lines and fixed and mobile phone lines. 

Though the scale of the impact is unclear, as is whether it has affected any Olympics activities, Marina Ferrari, the secretary of state in charge of digital affairs, posted on X that damage in several regions overnight affected telecommunications operators. She said that led to a localized impact on access to fiber lines and fixed and mobile telephone lines.

French travelers wait in train station

Hours away from the grand opening ceremony of the Olympics, high-speed rail traffic to the French capital was severely disrupted by what officials described as "criminal actions." (AP Photo/Mark Baker)

"I condemn in the strongest terms these cowardly and irresponsible acts. Thank you to the teams mobilized this morning to carry out repairs and restore damaged sites to service," Ferrari wrote. 

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A French police official told The Associated Press that at least six of France’s administrative departments were affected, which include the region around the Mediterranean city of Marseille, hosting Olympic soccer and sailing competitions. Telecom operators Bouygues and Free confirmed their services were affected. French media reports said lines operated by provider SFR were also hit. 

The parent company of Free said its teams are mobilized to restore services. 

The Associated Press contributed to this report.