Pollution in the River Seine has forced the cancellation of Monday’s swimming training for Olympic triathletes in Paris.

This is the second successive day training has been cancelled after Sunday’s ‘familiarisation’ session was called off for the same reason.

A statement issued on Monday by Paris 2024 and World Triathlon said that tests had shown the water quality was still below an acceptable standard and the organisations wanted to “reiterate that the priority is the health of the athletes”.

The men’s triathlon is due to start on Tuesday and, should the water quality not reach the required standard on race day, the triathlon events have two contingency days – 1 and 2 August – built into the programme.

If the water quality is not deemed suitable on those days, the swimming leg of the triathlon will be dropped and it will become a duathlon, with athletes competing over just the bike and running legs.

Tests earlier in July showed the River Seine was clean enough for swimming but heavy rain in the French capital on Friday and Saturday has seen the quality diminish.

The Paris 2024 and World Triathlon statement added: “The tests carried out in the Seine [on Sunday] 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 36 hours, Paris 2024 and World Triathlon are confident that water quality will return to below limits before the start of the triathlon competitions on 30 July.”

Significant rainfall can lead to untreated sewage being washed into the river but the statement added: “As observed in July, with summer conditions (more sunshine, higher temperatures, prolonged absence of rain) water quality in the Seine has improved significantly.”

Both open water 10km swimming events on 8 and 9 August could be relocated to Vaires-sur-Marne on the Marne River, east of Paris, if necessary.

The swimming leg of the triathlon familiarisation had been due to take place at 07:00 BST on Monday. The bike and running training are set to go ahead as planned.