The Olympics' triathlon swimming training session scheduled for Sunday has been cancelled after recent heavy rain in Paris affected pollution levels in the Seine, organisers said in a statement.
"The tests carried out in the Seine yesterday revealed water quality levels that in the view of the international federation, World Triathlon, did not provide sufficient guarantees to allow the event to be held," said Paris 2024.
"This is due to rain that has fallen on Paris on July 26-27."
Organisers said they were "confident" water quality would improve again before the triathlon events begin on Tuesday with the men's race.
The French capital has been working on cleaning up the Seine so people can swim in it again, as was the case during the 1900 Paris Olympics.

Dembele named FIFA player of 2025, Bonmati wins women's award
Australia's Green becomes IPL's most expensive overseas player
Jordan qualifies for the FIFA Arab Cup final
Sharjah Warriorz make it two in two with 11-run win over Gulf Giants
Bournemouth rescue draw with Man United in eight-goal thriller
