According to IAAF medics I am apparently suffering from food poisoning which has affected several other athletes in the athletes' hotel, Botswana's Isaac Makwala wrote on his Facebook page.
A number of athletes at the World Championships have been laid low by stomach upsets with Botswana's Isaac Makwala saying on Monday he was forced to withdraw from the 200m heats because of food poisoning.
London 2017 organisers released a statement late on Monday saying that a number of teams had reported cases of gastroenteritis at their official hotel.
"Those affected have been supported by both team and LOC medical staff, in addition we have been working with Public Health England to ensure the situation is managed and contained," the organising committee said in a statement.
"As a result, further advice and guidelines have been issued to team doctors and support staff -- standard procedure for such an occurrence where a number of teams are occupying championship accommodation."
It was not immediately clear if Makwala, who pulled out of the 200m heats earlier on Monday, was staying at the hotel in question but he said on his Facebook page that other athletes in his accommodation had been ill.
"According to IAAF medics I am apparently suffering from food poisoning which has affected several other athletes in the athletes' hotel," he wrote on his Facebook page.
"Lets hope they will allow me to run my final tomorrow."
Makwala, among the favourites for the 400m, would normally be scratched from the final after pulling out of another event.
As he missed the heats on medical advice, however, he would be able to run, if fit.
Ireland's 400m hurdler Thomas Barr was also forced out of his semi-finals on Monday.
"I wasn't feeling great yesterday evening and later in the night I was hit with a bad bout of gastroenteritis," Barr said in an Athletics Ireland statement.
"My whole year has been focused on the World Championships ... and I'm gutted to have to withdraw."