PARIS, France (AFP)— France’s rail network was paralysed Friday by coordinated acts of sabotage which knocked out most of its high-speed train services hours before the Paris Olympics opening ceremony.

French rail operator SNCF said three night-time arson attacks had destroyed cabling boxes at strategic junctions around its network at locations north, south-west and east of Paris.

A fourth attempted act of vandalism south-east of the capital was thwarted by rail workers who spotted intruders in the early hours of Friday.

“Our intelligence services and law enforcement are mobilised to find and punish the perpetrators of these criminal acts,” Prime Minister Gabriel Attal posted on X, calling the attacks “prepared and coordinated acts of sabotage.”

The Paris Olympics are set to open in a spectacular and unprecedented ceremony on the river Seine on Friday evening, with many ticket holders set to travel to the City of Light by train.

Several Eurostar trains between Paris and London were cancelled Friday because of the rail disruption, which is likely to affect British sports fans heading to the French capital.

The parade will see up to 7,500 competitors sail down a six-kilometre (four-mile) stretch of the Seine on a flotilla of 85 boats.

As well as the rail attacks, poor weather — with Paris under thick cloud and occasional rain — also risked dampening the party.

“We’ll see tonight… but the closer it gets the more the models suggest we’re likely to get rain,” chief Games organiser Tony Estanguet told France Inter radio, while adding that there would be some modifications if it was wet.

“It’s going to be a beautiful moment, it’s going to be a great party,” he added.

French security forces are on their highest alert to prevent terror attacks spoiling the start of the first Olympics in Paris in 100 years, while acts of sabotage from hostile foreign powers were also a known risk.

French officials refused to comment on the identity of the culprits of the rail sabotage who appear to have had a sophisticated understanding of the network.

Far-left French anarchists have a history of targeting the train network with arson attacks.

Suspicions might also fall on Russia, which French President Emmanuel Macron has said in the past was planning to target the Games.

Police arrested a Russian man this week in Paris who was suspected of “organising events likely to lead to destabilisation during the Olympic Games.”

Commenting on the rail disruption, which will affect 800,000 people over the weekend, International Olympic Committee president Thomas Bach told the media that he had no concerns.

“We have full confidence in the French authorities,” he said at the Athletes’ Village.

The USA basketball team was also set to take a high-speed train to play their opening a game on Sunday against Serbia in Lille, northern France.