POOR water quality in the Seine caused swimming training for the Paris Olympics triathlon to be cancelled today — but organisers remain confident the races will be able to go ahead as scheduled.

Triathletes were due to hold a familiarisation session in the river at 8am but organisers had warned on Saturday that it could be at risk and the decision was taken not to allow them into the water.

Heavy rain can raise the levels of harmful E Coli bacteria, and the deluge that marred the opening ceremony on Friday has had an effect.

More than €1 billion has been spent cleaning up the Seine to make it a central part of the games and, with better weather forecast until the individual triathlon races tomorrow and Wednesday, organisers are hopeful there will not be any delays.

A worst-case scenario could see the races changed to duathlons with the swimming leg removed entirely, but that appears unlikely.

A statement from the organising committee read: “The tests carried out in the Seine today 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.

“This is due to rain that has fallen on Paris on 26 and 27 July. Given the weather forecast for the next 48 hours, Paris 2024 and World Triathlon are confident that water quality will return to below limits before the start of the triathlon competitions.

“As observed in July, with summer conditions, water quality in the Seine has improved significantly. Paris 2024 and World Triathlon reiterates that the priority is the health of the athletes.”

The bike and running familiarisation sessions were able to go ahead as planned.

Britain has high hopes of medals in both the individual events and the team relay, and performance director Mike Cavendish is confident their chances will not be adversely affected.