Belgium will not take part in the Olympic triathlon mixed relay event on Monday after one of their athletes fell ill.

Claire Michel, who competed in the women's triathlon Wednesday, was hospitalized on Sunday before returning to the Olympic village later in the day.

Test swims in the Seine River scheduled for Saturday and Sunday before the triathlon mixed relay had to be canceled because of bacteria levels in the water.

However, organizers announced late Sunday that the mixed relay triathlon would take place on Monday at 8 a.m. local time (0600 GMT), as intended.

The Belgian Olympic Committee (abbreviated BOIC or COIB) said it hoped lessons would be learned in the future.

"Claire Michel, a member of the relay team, is unfortunately ill and must withdraw from the competition," the committee wrote in a statement.

"We are thinking here of the guarantee of training days, competition days and the competition format, which must be clarified in advance to ensure that there is no uncertainty for athletes, entourage and supporters," added the committee.

Bacteria levels in Seine under scrutiny

The mixed relay triathlon is scheduled for Monday, with the swim portion still slated to take place in the river.

World Triathlon's water safety guidelines and a 2006 European Union directive have assigned qualitative values to a range of E. coli levels.

Under World Triathlon's guidelines, E. coli levels up to 1,000 colony-forming units per 100 milliliters can be considered "good" and can allow competitions to go forward.

Organizers had said water quality tests done the day of the individual triathlon races on Wednesday had showed "very good" bacteria levels.

However, levels were too poor to allow practice for the mixed relay to go ahead on Saturday and Sunday.

More triathletes fall sick

Swiss officials said Saturday that triathlete Adrien Briffod, who also swam in the Seine on Wednesday, fell ill with a stomach infection. 

And, on Sunday, Briffod's replacement Simon Westermann also had to withdraw because of a gastrointestinal infection, although he had not participated in any swims in the Seine.

Meanwhile, Norwegian triathlete Vetle Bergsvik Thorn also became sick a day after competing in the men's triathlon.

Arild Tveiten, the sports director of the Norwegian Triathlon Federation, said the cause of Thorn's illness was unclear.

"We're thinking what everyone is thinking: that it's probably the river. But we don't know. It could be the river, it could be the chicken," Tveiten told Norwegian broadcaster NRK.

"The doctor is leaning toward the possibility of food poisoning. That's what the symptoms suggest."

km/jsi (Reuters, AP, AFP)