Speaking on Monday, the French leader said he was confident the planned ceremony, based on the River Seine, would go ahead but that France had "plan Bs, and even plan Cs" just in case.

The 26 July event is set to be the first Olympic opening ceremony held outside a stadium setting and will see about 10,500 athletes parade through the heart of the French capital of Paris on some 160 boats on the Seine along a 3.7-mile route.

However, with conflict in the Middle East and Russia's invasion of Ukraine combined with the threat of terror attacks, the French government has raised the security level to its highest level.

This has led to Mr Macron conceding that, if security demands necessitated, the Paris 2024 opening ceremony could be altered, or even scaled down.

He said France was not naïve, adding: "If we think there are security risks we'll have plan Bs, and even plan Cs." 

One option, Mr Macron said, would be to restrict the ceremony to the central Paris Trocadero square, facing the Eiffel Tower.

Another would be to move the event indoors, to the Stade de France.

An Olympic chief managing the opening ceremony previously spoke to Sky News about the issues surrounding security ahead of this summer's games.

Mr Macron gave the interview to BFM TV and RMC radio from Paris's Grand Palais museum, which has been refurbished to host fencing and taekwondo.

He also said he has not changed his mind about swimming in the Seine, which has been subject of a €1bn (£850m) clean-up project by authorities, and tried to convince a mother to let her son attend the opening ceremony.

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"If there is one place where your son will be safe it will be there. Let him go, it's once every 100 years, the Olympics," he said

The mum said she hoped her son would be at work on the day of the ceremony, and unable to attend.

Mr Macron is standing by his pledge to swim in the Seine, and Paris mayor Anne Hidalgo is promising the same - over 30 years since her predecessor Jacques Chirac promised to do so but never did.

Despite the clean-up operation so people can swim in the Seine once more, as they did during the 1900 Paris Olympics, it still is not clear whether it will be definitely safe in time.