French high-speed rail lines disrupted by 'sabotage' ahead of Olympics opening ceremony in Paris
Rail operator SNCF said the "malicious attacks", which included arson attacks, will impact 800,000 passengers over the weekend.
SNCF chief executive Jean-Pierre Farandou said the cables will have to be repaired "one by one".
The opening ceremony will see up to 7,500 competitors travel down a six-kilometre stretch of the river Seine on a flotilla of 85 boats.