French President Emmanuel Macron speaks to journalists. GETTY IMAGES

French President Emmanuel Macron said on Monday that the opening ceremony of the Paris Olympics could be moved from the Seine to the national stadium in the event of a security threat.

Macron said in an interview that instead of the teams sailing down the Seine on barges, the opening ceremony could be "limited to the Trocadero" building in front of the Eiffel Tower or "even moved to the Stade de France".

The Paris organisers have devised a ceremony that is unprecedented in Olympic history, breaking with the tradition of opening the Games in the main stadium, but with the Olympics taking place as war rages in Ukraine and Gaza, the ceremony also leaves the teams potentially vulnerable to attack - French authorities have raised the possibility of a drone strike.

So far, organisers have denied that the ceremony on 26 July could be moved to another venue if authorities believe it could be targeted.

"This opening ceremony... is a world first. We can do it and we are going to do it," Macron said in an interview with BFMTV and RMC, but added: "There are Plan Bs and Plan Cs", including moving the ceremony to the Stade de France to the north of Paris, the main stadium for the Olympics where the rugby sevens and athletics will be held.

The French President symbolically kicked off the countdown to the Paris Olympics this Monday, first with an interview on BFMTV and RMC at 8.20am, followed by a tour of the Grand Palais in Paris.

Macron was interviewed by journalist Apolline de Malherbe, surrounded by RMC's Olympic advisors, former athletes David Douillet (judo), Marion Bartoli (tennis) and Rémy Boullé (paracanoe).

Moving the ceremony from the Seine would be a huge undertaking and would deprive the Paris Olympics of its defining image. "We will analyse this in real time," Macron stressed.

More than 300,000 spectators are expected to attend the ceremony, with another 200,000 watching from buildings along the Seine. So far, all countries have said they will take part in the open-air river parade, including the most risk-averse, such as the United States and Israel.

Three months before the opening ceremony and with international clouds gathering, two days after Iran's attack on Israel. Macron said he wanted to "do everything possible to have an Olympic truce" for the Paris Games, despite the war raging in Ukraine and elsewhere.

"We want to work towards an Olympic truce and I think this is an opportunity for me to engage with many of our partners," he told BFMTV. The truce is a historic tradition of peace during the Olympic Games.

The world's most eagerly awaited event is taking place in a complex global context. Russia's war in Ukraine and the conflict between Israel and Hamas in Gaza are complicating efforts to secure the Olympics, which will be held in France from 26 July to 8 September and are expected to attract at least 10 million spectators.