French rail company SNCF has warned that disruption from Friday’s sabotage against the country’s train network could last until the end of the weekend and affect hundreds of thousands more passengers.

Coordinated arson attacks on three lines of the high-speed TGV network on Friday caused chaos for travellers, hours before the opening ceremony for the Paris Olympics. A fourth attack was thwarted by rail workers.

Prime Minister Gabriel Attal described the attacks as “acts of sabotage”.

About a quarter of international Eurostar trains were also cancelled, with UK Prime Minister Keir Starmer among those affected.

In a statement issued on Friday evening, SNCF said traffic “would improve” on affected lines on Saturday thanks to the work of thousands of rail workers.

It said:

• On the eastern line, trains would run normally from 06:00 (05:00 BST) on Saturday
• On the northern line, 80% of trains would be running, with delays of 1-2 hours
• On the south-western line, 60% of trains would be running, with delays of 1-2 hours

The company added that customers whose trains are delayed or cancelled will be contacted by email or text message.

Eurostar said it expected about a fifth of services over the weekend would be cancelled, while all trains would face delays of around 1.5 hours. Eurostar services use the northern high-speed line.

SNCF said surveillance of the rail network had been strengthened “on land and in the air,” using 1,000 workers and 50 drones.

Junior Transport Minister Patrice Vergriete said around 250,000 people had been affected on Friday, while up to 800,000 could face delays and cancellations by Monday.

He added that disrupting holiday travel, rather than Friday’s Olympic opening ceremony, was the most likely aim of the saboteurs.

“There is not necessarily a link” with the Olympics, he said in an interview.

Friday 26 July traditionally marks the start of the grand départ (big getaway) for many French holidaymakers heading out of the cities.

No group has yet claimed that it was behind the attacks. A source linked to the investigation told the AFP news agency that the operation was “well prepared” and organised by “a single structure”.

Mr Attal said security forces were searching for those responsible.

At around 04:00 on Friday, saboteurs cut and set on fire specialised fibre optic cables essential for the safe functioning of the rail network, government officials said.

One site was at Courtalain, 150km (93 miles) south-west of Paris. A picture posted online purportedly showed burnt-out cables in a shallow gulley with its protective SNCF paving stones discarded.

The SNCF spoke of a “massive, large-scale attack aimed at paralysing” its services, not just at Courtalain but at Pagny-sur-Moselle, a village outside the eastern city of Metz and Croisilles, not far from the northern city of Arras.

Another attempted attack in Vergigny, south-east of Paris, was foiled by SNCF workers who were carrying out maintenance on site in the early hours of Friday.

Prosecutors have opened an investigation into attacks on “the fundamental interests of the nation”.