The French government announced Wednesday that it had slashed the number of spectators attending the opening ceremony of the Paris Olympics amid security and other organisational challenges.

The traditional opening parade of Olympic sporting delegations is set to take place in boats on the river Seine on 26 July, the first time the ceremony has been held outside the main athletics stadium.

After months of speculation about the size of the crowd permitted to watch the flotilla, Interior Minister Gerald Darmanin told the France 2 channel on Tuesday "around 300,000" ticketed spectators would attend.

He had earlier referred to around 600,000 when speaking in the Senate in October 2022, while other members of the government and organisers had spoken of 400,000-500,000.

"I know that we have the best security forces in the world and that we will succeed in showing that not only that we can win medals (at the Olympics) but that we can play host to the world without any problems," Darmanin told the channel. 

The idea of the open-air ceremony has been resisted by some senior figures in the security forces because of the difficulty of managing such large crowds and the risk of terror attacks.

Authorities have also had difficulties in persuading the traditional booksellers who line the river from temporarily removing their kiosks in order to make space for spectators.

Organisers had pushed for as large a crowd as possible in order to fulfil their vision of a "people's Olympics" that would make the Games accessible to a maximum number of French fans.

Darmanin said that 100,000 tickets had been sold for the best vantage points for the opening ceremony on the lower banks of the river, while another 200,000 would be given free access to the upper banks of the Seine. 

The figure of 300,000 people did not include others "who live and who will be able to rent to have parties along the Seine", Darmanin added, referring to the hundreds of buildings that overlook the famed waterway. 

France was at its highest alert for terror attacks from October to January 15 after a suspected Islamist burst into a school in northern France and stabbed a teacher to death. 

"The terror risk is extremely strong," Darmanin said on Wednesday.