International Olympic Committee president Thomas Bach says he has “full confidence” in the French authorities after arson attacks on the train network delayed thousands of travellers just hours before the Games’ opening ceremony.

A series of fires has badly affected several high-speed rail lines within Paris, with around 800,000 people expected to be affected.

Rail company SNCF described it as a “massive attack aimed at paralysing the network”.

The Eurostar has also advised passengers not to travel and cancelled some services.

The opening ceremony is set to begin in Paris at 19:30 (18:30 BST), with boats travelling down the River Seine and the city’s mayor Anne Hidalgo said the issue would have “no impact” on the event.

“I don’t have concerns, we have full confidence in the French authorities,” Bach told the BBC.

“All the measures are being taken. The French authorities are assisted by 180 other intelligence services around the world.

“We have good reason to have full confidence.”

SNCF said on Friday that signal boxes had been damaged by fires in a “massive attack”, affecting lines that connect Paris to cities in the north, east and south west of the country.

The company said further disruptions would take place over the weekend.

Christophe Dubi, the Olympic Games executive director, told the BBC he had seen a “quick reaction” from organisers.

“The organisers, including authorities and SNCF, have to prepare for different scenarios,” he said.

“What I see here is a quick reaction and that gives me a lot of confidence.

“I have to feel for all those impacted by these delays, but I have confidence that organisers are really well prepared for any situation and this is definitely one.”

Prime Minister Gabriel Attal described it as “co-ordinated and prepared acts of sabotage”.

Eurostar, which has trains from London to Paris, has encouraged passengers not to travel after delays and cancellations.

“Paris 2024 has taken note of incidents affecting the Atlantic, North and East lines of the SNCF rail network,” read a statement from Games organisers.

“We are working closely with our partner, the rail operator SNCF, to assess the situation.”

The Paris prosecutor’s office has opened a criminal investigation into the incident.

Amelie Oudea-Castera, the country’s sports minister, said it was an attack on “the athletes’ Games”.

“These Games are for the athletes who have been dreaming of them for years, fighting for the holy grail of standing on the podium, and someone’s sabotaging that for them” she told French broadcaster BFMTV.

The rainy weather has also caused some delays in Paris.

A scheduled news conference with Tony Estanguet, the president of the Games, was cancelled on Friday, reportedly because of the weather, external and its possible impact on the opening ceremony.

The Olympic torch procession has, however, continued throughout the day.

It is the first time a summer Olympics opening ceremony has been held outside the main athletics stadium.

It is expected to last just under four hours and will also include the official opening of the Games, carried out by President Macron, and the lighting of the Olympic cauldron.