Eurostar and other French high-speed rail networks were thrown into chaos on Friday as a series of arson attacks disrupting travel to Paris only hours before the Olympic opening ceremony.
Prime Minister Gabriel Attal saying there would be "massive and serious" consequences both for people trying to travel to Paris and for those heading to other parts of the country or across the Channel.
National rail company SNCF said its Atlantic, North and East networks were damaged in the incidents, with fires laid across the tracks, while an attempted attack in the South-East was foiled.
Trains from London to Paris and Lille were being delayed by around an hour and a half, with a quarter cancelled. Eurostar said this would remain the case over the weekend, with the service not back to normal until Monday.
All high-speed trains to and from Paris have been diverted to a slower line and the company urged customers to postpone their journeys if possible.
Prosecutors in Paris opened a national investigation, saying the crimes could carry sentences of 15 to 20 years.
French rail operator SNCF said the situation should last “at least all weekend” but that teams were already on site carrying out checks and beginning repairs.
