The Paris organising committee said in a statement a search was underway at their headquarters in the suburb of Saint-Denis, and that "Paris 2024 is cooperating with the investigators to facilitate their investigations."
Paris becomes the third straight Summer Games organiser implicated in a corruption probe.
Vote-buying allegations linked to the 2016 Rio de Janeiro Olympics and the Tokyo Games in 2021 previously removed several members of the International Olympic Committee from their posts.
An official with the financial prosecutor’s office said the searches are linked to two preliminary investigations related to the Paris Olympics that had not previously been made public.
According to Le Monde newspaper, raids also took place at the offices of the public body in charge of Olympic infrastructure, and at the headquarters of several companies and consultants linked to the organisation of the games.
One of the probes was opened in 2017 (the year Paris was picked by the IOC as the 2024 host) into suspected embezzlement of public funds and favouritism.
The other was opened in 2022 following an audit by the French Anti-corruption Agency.
The prosecutor’s office said the case targets suspected conflict of interest and favouritism involving several contracts reached by the organising committee and Solideo, the company in charge of Olympic facilities.
The raids unfolded at the same time as the IOC executive board began a two-day meeting in Lausanne, Switzerland, expecting to praise Paris organisers for their progress.
"We are aware that there has been a search by police of the Paris 2024 headquarters today," an IOC spokesperson said.
"We have been informed by Paris 2024 that they are cooperating fully with the authorities in this matter."
The total budget of the Games has soared to 8.8 billion euros (£7.54bn) from an initial assessment of 6.6bn (£5.66bn) in 2017.
The infrastructure alone is expected to cost 4bn euros (£3.43bn) from an original estimate of 3.2bn (£2.74bn).
IOC president Thomas Bach told reporters on Monday the meeting would be about Paris "where we have some good news."
The investigation is the latest in a series of scandals that have rocked French sports in recent years.
In May, the president of the French Olympic Committee resigned following a period of intense infighting.
In February, Noël Le Graët resigned as president of the French football federation after a government audit found he no longer had the legitimacy to lead because of his behaviour toward women and his management style.
Bernard Laporte resigned as president of the French Rugby Federation in January after he was convicted of corruption and illegally acquiring assets and handed a suspended prison sentence.
Last October, Claude Atcher was fired as chief executive of the 2023 Rugby World Cup following an investigation into his workplace conduct.
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