France’s high-speed rail network was hit by “malicious acts” including arson attacks that have disrupted the transport system, train operator SNCF said Friday, hours before the opening ceremony of the Paris Olympics.

A source close to the investigation told Agence France-Presse the attacks were coordinated acts of “sabotage.”

“This is a massive attack on a large scale to paralyze the TGV network,” SNCF told AFP, adding that many routes will have to be cancelled.

“SNCF was the victim of several simultaneous malicious acts overnight,” the national train operator said, adding that the attacks affected its Atlantic, northern and eastern lines.

“Arson attacks were started to damage our facilities,” it said, adding that traffic on the affected lines was “heavily disrupted” and the situation would last through the weekend as repairs are made.

Trains were being diverted to different tracks “but we will have to cancel a large number of them,” the statement said.

The southeastern line wasn’t affected as “a malicious act was foiled,” the operator continued.

SNCF urged passengers to postpone their trips and stay away from train stations.

Transport Minister Patrice Vergriete called the “massive attack” against the TGV rail network an “outrageous criminal act.” 

There will be “very serious consequences” for rail traffic throughout the weekend with connections toward northern, eastern and northwestern France halved, Vergriete said. SNCF chief executive Jean-Pierre Farandou said 800,000 passengers were affected.

The Associated Press reports that Sports Minister Amélie Oudéa-Castera said authorities were working to “evaluate the impact on travelers, athletes, and ensure the transport of all delegations to the (Olympic) competition sites.”

“Playing against the Games is playing against France, against your own camp, against your country,” she said on BFM television,  without identifying whoever was behind the vandalism.

Paris police chief Laurent Nunez, speaking on France Info radio, said he would send police reinforcement to train stations overcrowded as a result of the incidents.

The attacks were launched as Paris was under heavy security ahead of the opening ceremony of the Summer Olympics, with 300,000 spectators and an audience of VIPs expected to attend.

A parade on Friday evening will see up to 7,500 competitors travel down a four-mile stretch of the river Seine on a flotilla of 85 boats.

It will be the first time a Summer Olympics has opened outside the main athletics stadium, a decision fraught with danger at a time when France is on its highest alert for terror attacks.

At Paris’s Montparnasse train station, dozens of passengers were waiting for more information about their trips after delays of 30 minutes to almost two hours were announced.

“Normal traffic is expected to resume on Monday, July 29,” read one of the signs in the departure hall.

“We arrived around 7:00 am but we were told that we might not be able to leave before Monday,” said a 27-year-old student, Jocelyn, who’d planned to travel to Bretagne and refused to give her full name.

“We expected it to be a bit chaotic in Paris with the opening ceremony scheduled for this evening, but we didn’t think it could be this bad,” she said.