An Olympic swimmer was forced to withdraw from a mixed relay triathlon after falling ill due to deteriorating water quality in the Seine River.

The Seine River was the subject of much controversy during the Games, with many concerned about the quality of the water, fearing it could contain dangerous levels of E. coli.

French Sports Minister Amélie Oudéa-Castéra tried to prove it was safe to jump into a river 13 days before the Games began, but many on social media were not convinced by her claim.

Olympic organisers said around €1.4bn (£1.2bn) had been spent on a regeneration project to keep the River Seine safe, but the river has been plagued by problems affecting the Games and the men’s triathlon was postponed by a day.

Beyond that, the mixed relay practice on Sunday (August 4) has been postponed for another day.

There is likely to be more controversy after the Belgian team withdrew from the mixed relay triathlon due to illness of one of its athletes, Claire Michel.

Claire Michel’s illness has forced her team to withdraw from the mixed relay triathlon. (JASPER JACOBS/BELGA MAG/AFP via Getty Images)

Despite previous reports, a source from the Belgian team told BBC Sport that the 35-year-old athlete had not contracted E. coli.

They added that they could not definitively suggest that Michel’s illnesses were linked to the Seine River, where the swimming tours take place.

The Belgian Olympic Committee (COIB) confirmed that Michel went to the outpatient clinic in the Olympic Village but was not taken to hospital.

The COIB said the decision not to participate in the games was taken ‘in consultation with the athletes and entourage’, although it has not yet been confirmed what illness the girl is suffering from.

Olympic sports held on the Seine River have become a subject of controversy. (Christian Petersen/Getty Images)

A joint statement from World Triathlon and Paris 2024 said: “The latest test results confirm that the water quality of the Seine at the triathlon venue has improved in recent hours. Prospective analysis shows that the water quality will be at levels acceptable to World Triathlon.”

In addition, the Swiss team announced on Saturday (August 3) that one of its athletes in the men’s race, Adrien Briffod, had a stomach infection and therefore would not be able to compete in the mixed relay.

Swimming in the Seine has been banned for more than 100 years due to high pollution and disease risks, but French authorities have invested heavily to ensure the river is swimmable for the Olympics.