France has foiled four different plots to sabotage the Paris Olympics over the last few weeks, the French interior minister said on Friday without giving further details. 

The comments came after three of the country’s four high-speed lines were hit by arson attacks on the day of the opening ceremony, impacting up to 800,000 travellers. 

Signals along the tracks were set on fire and cables cut and set alight in a series of “coordinated” strikes that brought train services around the capital to a standstill, sources close to the investigation said. 

Nobody has so far claimed responsibility, but French intelligence and US officials said that the incident could have been the work of anarchists or extreme Left-wing groups. 

Some senior French officials have pointed the finger at Russia, whose athletes are barred from this year’s Olympic Games. 

Israel said that Iran was responsible, with foreign minister Israel Katz writing on social media that the attack was “planned and executed under the influence of Iran’s axis of evil and radical Islam”. 

Patrice Vergriete, acting transport minister, said the authorities were “preparing themselves” for more such incidents. 

SNCF, France’s national state-owned railway, said it would ramp up security to enable trains to run tomorrow. 1,000 workers, 40 railway police teams and 50 drones would be deployed to monitor the rail network, the company said.

Travel disruption will continue into the weekend. In a statement earlier on Friday, Eurostar confirmed it would be cancelling one in four services across its network on Saturday and Sunday.

One to two-hour delays are also expected across the French high-speed rail network. 

Repairing sabotaged fibre-optic cables will be a complex and painstaking job, French officials said earlier on Friday. 

“We need to find all the experts … who have the capacity to repair, as well as the tools and parts, since we’re talking about technical cables that aren’t the kind of cables you find everywhere,” Franck Dubourdieu, a regional train director, said. 

 “We’re in the process of bringing them in from different parts of France to be able to repair them as quickly as possible,” he added. 

It is understood that the cables were used to relay safety information, such as red light signals, to train drivers.