Paralympic organisers on Sunday postponed the triathlon by a day over worries about the River Seine's water quality.

"The latest analysis shows a deterioration in the water quality of the Seine following heavy rainfall over the past two days," the organisers said.

"It was decided to schedule the 11 medal sessions of the Para triathlon on September 2," they added, following a meeting between World Triathlon, the Paris 2024 organisers, and the relevant French authorities.

The triathlon was originally scheduled to happen over two days -- September 1 and 2.

The issue also caused disruption to the Olympics triathlon and open-water swimming events, with several practice sessions being cancelled due to high levels of pollution caused by heavy rainfall.

Of 11 days of events and training scheduled in the river during the Olympics, only five got the green light.

Despite a 1.4 billion euros ($1.5 billion) upgrade to improve the Paris sewerage and water treatment system, the Seine has been dogged by pollution concerns, notably for its levels of enterococci and E.coli bacteria.