Rail workers foiled an attempt to destroy safety equipment on the fourth line.
“At this stage, traffic disruption will remain on the Northern Axis on Sunday, with conditions improving on the Atlantic Axis over the weekend,” a rail network spokesperson said on Saturday morning.
SNCF estimated on Friday that around 250,000 passengers were affected, while Deputy Transport Minister Patrice Bergriette said up to 800,000 could be affected over the three days.
Eurostar, which operates international routes from London to Paris and uses France's high-speed rail network, said one in four trains would be grounded over the weekend.
Travellers have been advised to postpone their trips, and the suspension is expected to last until Monday.
Among the Eurostar passengers affected on Friday was Prime Minister Sir Keir Starmer, who had been due to take the train to the Olympic opening ceremony but was forced to fly instead.
