The Olympic men’s individual triathlon at Paris 2024 has been postponed after tests revealed water quality in the River Seine did not reach the required standard.

The race was due to start at 07:00 BST (08:00 local time) on Tuesday and will now take place on Wednesday at 09:45 (10:45 local time), following the conclusion of the women’s event.

Swimming training sessions were cancelled on Sunday and Monday because of the water quality, which was impacted by recent heavy rainfall.

Friday, 2 August remains a contingency date for both races, while organisers have said the event could be contested as a duathlon as a last resort.

“Tests carried out in the Seine today revealed water quality did not provide sufficient guarantees to allow the event to be held,” World Triathlon said.

“Despite the improvement in the water quality levels, the readings at some points of the swim course are still above the acceptable limits.”

Great Britain’s Alex Yee is one of the favourites for gold in the men’s race, while team-mate Beth Potter is the reigning women’s world champion.

Tests are being carried out daily on the water quality in the River Seine, which is also due to host the triathlon mixed relay on 5 August, the Olympic marathon swimming on 8 and 9 August, and the Para-triathlon event at the Paralympics, which start on 28 August.

Organisers said about 1.4bn euro (£1.2bn) had been spent on a regeneration project to make the Seine safe to swim in after a 100-year-old ban.

But as recently as June this year the level of E. coli was 10 times the acceptable level imposed by sports federations.

Paris mayor Anne Hidalgo recently swam in the river to highlight the clean-up efforts which have been undertaken and, earlier this month, tests showed the river was clean enough for swimming.

However, heavy rain in Paris on Friday and Saturday has caused the water quality to diminish and, at a meeting held at 03:30 local time, the decision was taken to postpone the event.

Paris organisers remained confident on Monday that the men’s race would go ahead on Tuesday morning.

Thundery showers are forecast for Wednesday morning, following predicted hot temperatures of up to 35C on Tuesday.

“In the case of triathlon the heat has a positive effect because the sunlight and the increased temperature is beneficial in the sense that it kills bacteria,” Paris 2024 operations director Lambis Konstantinidis told BBC Sport.

Organisers have extreme heat contingency plans for each sport and venue and some sports have a specific temperature threshold where play cannot continue if exceeded.