Will Macron’s ‘bold’ Olympic opening ceremony be a flop? Hours before it starts, Paris is hit by chaos on public transport as railway lines are vandalised and meteorologists predict torrential rain during the six-kilometre river parade

Paris has promised an Olympic opening ceremony as grand as anything seen before, but travel chaos, “malicious” acts of vandalism and forecast rain threaten to spoil the parade.

Emmanuel Macron’s “bold” plans call for the River Seine to be used as a stage for a four-mile-long procession, with athletes travelling on boats in front of more than 300,000 spectators.

The show is set to start at 19:30 (18:30 BST), with forecasters predicting a high chance of torrential rain in the French capital, and officials praying the open-air party will not be a flop.

With the ceremony the first in history to be held outside a stadium, ensuring the safety of sports stars, dignitaries and the public will be an unprecedented security challenge, with French officials calling it “the largest operation ever undertaken in peacetime.”

Police are on high alert amid threats of a terrorist attack after vandals targeted rail infrastructure overnight in a series of coordinated arson attacks, and organisers fear further acts of sabotage could target the Games.

Just hours before the opening ceremony, fires broke out early this morning at key facilities on the railway network, halting trains.

The “coordinated” attacks brought major stations to a standstill and cancelled multiple services, including those bringing sports fans into the French capital.

UK travellers heading to the Games have been seen queuing at the Eurostar terminal at St Pancras station in central London due to the disruption, which threatens to affect tonight’s show.

The procession of athletes will be the first boat parade on the Seine since the wedding of Louis XV’s daughter three centuries ago, and images of the preparations show how it will nod to French culture and history.

Hundreds of thousands of people pay to stand on bridges and along the river, but it is unclear how the spectacle will be protected from possible bad weather.

He Meteorological Office A high chance of rain is forecast for the French capital tonight, increasing from 50 percent at the start of the ceremony to almost 100 percent certainty of rain by 11 p.m.

At the same time, crowd control will be a major concern as people rush to get to the city centre before it closes.

Operation Ring of Steel will see security measures spread across the city, rather than just in centralised locations like the London 2012 Olympics.

Some 45,000 police and gendarmes, including British and foreign police, are being mobilised, as well as 10,000 soldiers.

Security forces were deployed along the six-kilometre (6-mile) length of the ceremony, with high-precision snipers on rooftops and helicopters hovering overhead.

For the first time, France’s three elite units (RAID, GIGN and BRI) will work together, with a combined force of 650 troops.

The Air Force is also mobilized to secure the skies and combat any drones flying over the ceremony.

Metal barriers have been erected along the Seine and around the streets and boulevards, and spectators are having their bags inspected and are asked for special QR codes as they pass through the gates.

The UK Foreign Office has warned tourists: ‘Until Friday 26 July, you will need a digital pass to travel to some areas of Paris due to preparations for the Olympic opening ceremony.

‘Different rules will apply depending on whether you are travelling on foot, by bicycle, by car or other vehicle.’

“It is the biggest security challenge that any country has ever had to deal with in peacetime,” Interior Minister Gérald Darmanin told reporters on Tuesday.

A no-fly zone the size of Belgium will be imposed over northern France during the ceremony amid fears of a terrorist attack.

All three Paris airports will be closed from early afternoon until around midnight, causing severe travel disruption on what is typically one of the busiest days of the summer.

The French Civil Aviation Authority said in a statement: “A temporary no-fly zone has been created to ensure the implementation of special air security measures as part of the protection of the opening ceremony of the Paris 2024 Olympic Games.”

Olympic organisers have long feared acts of sabotage against the multi-billion pound games, and a vast £350m security operation has been launched in Paris to try to counter the threats.

The largest peacetime deployment of forces in French history involves some 75,000 soldiers, police and private security agents.

“We are focused and ready,” said Gen. Lionel Catar, one of the military planners before the inauguration.

The priority is to protect the 80,000 or so competitors who will sail down the Seine in dozens of barges, in front of some 350,000 spectators and a television audience of more than one billion.

French Interior Minister Gérald Darmanin said that “the terrorist threat remains high” and that “a high level of vigilance” remains essential.

France, which has a history of terrorist attacks, is on high alert ahead of the Games, including tonight’s opening ceremony.

In May, police arrested an 18-year-old man suspected of planning a jihadist attack at the Saint-Etienne stadium, the venue for the Olympic football matches.

Last week, a neo-Nazi was arrested on suspicion of planning an attack during the Olympic torch relay.

As part of their massive crackdown on crime ahead of the Games, French authorities moved hundreds of squatters out of the centre and jailed hundreds of people in an effort to clean up the streets.