PARIS (AP) — Paris Olympics organisers and other officials cancelled a paratriathlon swimming test event Saturday in the Seine River because of new concerns about water quality.

The competition was transformed into a duathlon instead, involving just running and biking. The cancellation is a fresh blow both to organisers of the 2024 Summer Games and to the city’s ambitions to reopen the iconic river to public swimming after next year’s Olympics.

Swimmers took to the Seine in competition on Thursday and Friday, but results of water quality tests showed “significant discrepancies” in the hours leading up to Saturday’s events, organisers said in a statement.

It said officials from World Triathlon, the Paris Olympics, Paris City Hall and the Paris region jointly decided to cancel Saturday’s events “as a measure of precaution, to not put the health and safety of the athletes in danger.”

A previous test event had to be cancelled earlier his month because heavy rain had caused overflows of untreated waste in the Seine, leaving water quality below safety standards. Rainfall also hit Paris ahead of Saturday’s cancellation.

New tests will be conducted and a decision will be made early Sunday on whether Sunday’s swimming events can be held as scheduled, organisers said.

France’s capital city is spending massively on water-management projects that officials say will make pollution caused by storms less frequent.

The triathlon event takes athletes and spectators — watching for free — to some of the French capital’s most striking vistas: The swimming portion of the race starts from the bottom of the spectacular 19th century Alexandre III bridge and its golden statues. The bike and run laps go along the Champs-Elysees avenue and through some of the most prestigious neighbourhoods of Paris.