A review of the course at Sentosa Island found water quality levels “exceeding acceptable thresholds”, with organisers making the decision to postpone “in the utmost interest of athlete safety”.

The women’s 10km race was set to take place this morning but has been pushed back to Wednesday, when the men’s event will also be held.

“World Aquatics regrets the inconvenience caused by the postponement and acknowledges the commitment and preparation of all athletes, coaches and teams,” World Aquatics said in a statement.

“The health and safety of participants remain the highest priority in all competition-related decisions.”

World Athletics said tests had “consistently” shown the water quality to be acceptable but that a sample taken on Sunday went over the limit.

Pool swimming events at the world championships begin on July 27.