Authorities in France on Monday continued a probe into the possible involvement of far-left extremist groups in a major attack against the country's rail network that disrupted high-speed trains over the weekend.

The newspaper Le Figaro said an activist linked to a far-left movement was arrested at a "railway site" in Oissel on Sunday.

The suspect allegedly had access keys to SNCF technical premises, tools and far-left literature, the AFP news agency reported, citing police sources.

Separately, Interior Minister Gerald Darmanin said the saboteurs' methods bore the hallmarks of far-left extremists.

"We have identified the profiles of several people," Darmanin told France 2 TV.

"This is the traditional type of action of the ultra left," he added.

However, Darmanin warned against jumping to conclusions because the perpetrators could have been manipulated.

"We must be cautious," he said.

High-speed trains up and running

High-speed trains were operating back to normal on Monday after the attack disrupted transport over the weekend, coinciding with the opening of the 2024 Olympics in Paris.

Transport Minister Patrice Vergriete said the cost of the sabotage would "very probably" amount to millions of euros. He told the broadcaster RTL that this included "commercial losses" and "repair costs."

In response to the incident, Darmanin said that 50 drones, 250 rail security agents and 1,000 maintenance workers were deployed to tighten security along the 28,000-kilometer (17,400-mile) high-speed train network.

Darmanin also confirmed that authorities had arrested 45 members of the Extinction Rebellion direct action environmental group. They had planned actions to protest the social and ecological consequences of the Olympics.

Meanwhile, in a new incident, police said the fibre optic networks of several telecommunications operators had been "sabotaged" in six areas of France on Monday.

zc/rc (Reuters, AFP)