Levels of pollution in the Seine River have forced the para-triathlon test event at the Paris Olympics to be postponed.

According to the Paris mayor's sports assistant Perre Rabadan, the sample contained levels of E.coli "slightly too high."

This comes after a test open water swim competition for the 2024 Games was canceled a fortnight ago owing to severe pollution.

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The para-triathlon trial event was reduced to cycling and running alone, with the mixed relay triathlon Sunday possibly seeing the same fate. A decision is due tonight, according to international triathlon secretary general Antonio Arimany.

Test events went ahead this week in the French capital's river without any issues.

Briton Beth Potter won the women's triathlon on the Seine, while Alex Yee won the men's test event on the same route that will be used at next year's Games.

As organizers probed the cause of Saturday's increased E. coli readings, Tony Estanguet, the president of the Paris 2024 organizing committee, emphasized that there was no 'Plan B' for next year's athletic spectacular.

Estanguet pressed that there was "no solution to move the event, the triathlon and open water swimming will be held in the Seine next year."

On August 6, after completing tests on the Seine River's water, the International Swimming Federation canceled the pre-Olympics swimming test competition.

"Water quality in the Seine has remained below acceptable standards for safeguarding swimmers' health," a statement issued by World Aquatics read.

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Paris Mayor Anne Hidalgo had made a promise that from 2025, three sites where swimming had been prohibited since 1923 would reopen. 

In the past, Olympic swimmers have protested water quality in previous host countries. In 2019, swimmers ahead of the Tokyo Olympics complained that the water in Tokyo Bay was too polluted. Likewise, in 2016, swimmers protested the water quality in Guanabara Bay during the Rio Olympics. 

On August 5, 57 swimmers who competed in swimming events at the World Triathlon Championship Series in Sunderland, Britain, fell ill and suffered from vomiting and diarrhea.

Nearly 2,000 individuals gathered for the event, which included a swim off Sunderland's blue flag Roker Beach. The UK Health Security Agency, or UKHSA, stated that samples from people who were unwell will be tested to determine the cause of illness and any common parasites.

On Wednesday, July 26, three days before the incident, an Environment Agency survey at Roker Beach did sampling, which showed 3,900 E Coli colonies per 100ml, more than 39 times higher than usual readings the previous month. E coli is a bacterial infection that can cause abdominal discomfort and bloody stools.