However, the head of Solideo, the company in charge of the project, is adamant that everything will be in place in time for the start of Paris 2024. 

Of the 70 sports venues being prepared for the Paris 2024 Olympic Games, only three are behind schedule compared to the work plan that was drawn up by the project managers. This was reported by AFP. The head of Solideo, the company in charge of the infrastructure, was quoted as saying. 

The three areas that will have to be adapted to the timetable are part of the Athletes' Village, the largest installation of the French Olympic Games, the renovation of the Grand Palais monument in the centre of Paris, where the fencing events will be held, and the Colombes training pool in the north of Paris. 

The latter requires special supervision and is due to be completed in June. According to officials, the 70 sites are expected to be completed by the deadline.

Nicolas Ferrand told a hearing of the French Senate's sports commission: "There are three sites out of 70 that are being monitored without compromising the schedule. "Overall, the work is fully on schedule and within the budget given to us and the level of ambition set," he added. 

It is not just the sports facilities that are in the best possible condition for athletes to use. Other areas are also on schedule. There is a crucial extension of the metro line in the north and south of Paris that must be completed before the big sporting event begins. The organisers are optimistic about this too 

Michel Cadot, head of the Olympic Games Coordination Committee and director of the National Sports Agency, also assured the Senate committee that Paris 2024 would be "perfectly on time and on budget".

The opening ceremony on 26 July will be one of the most spectacular events in history. It will be unprecedented in that it will be held outdoors. Cadot said: "The size of the crowd is still being discussed," he admitted. Organisers initially said 600,000 people would attend, most for free, but the latest estimate, according to police and political sources, is 500,000. 

It will not be easy, and indeed the opening ceremony is one of the most time-consuming tasks for the organisers. It has been the subject of much criticism, always on the grounds of security. 

There has been speculation about a possible 'Plan B', an alternative that would see a return to the usual venue at the athletics stadium. However, on Wednesday last week, Cadot ruled out this option as the stadium would be occupied by a rugby match at that time.

Contingency plans include "adapting the concept of the Seine", as he put it. There have been reports that athletes could be withdrawn in the event of a high risk of terrorist attack. 

The Seine will play a dual role. On the one hand, it will be the setting for the opening ceremony of the Olympic Games. It will also be the venue for the open water swimming and triathlon events, once the water has been cleaned. 

"The work is progressing very well, with remarkable results that are already visible," he told the senators. Poor water quality meant that three swimming trials had to be cancelled last July and August.