Wayde van Niekerk (RSA) set a Meeting Record of 43.73 in the Men's 400m at the 2017 Herculis EBS in Monaco Photo Credit: Philippe Fitte / IAAF

Botswana's Isaac Makwala, one of the favourites for medals in both the men's 200m and 400m here at the IAAF World Championships in London has been struck down with a stomach bug.

Makwala pulled out of the men's 200m Heats last night after coming down with a stomach upset shortly after dinner on Sunday and was put in 'quarantine', according to his teammate Lydia Jele.

As many as 30 athletes competing in the IAAF World Championships, lodging at the Guoman Tower Hotel in central London, are said to have been affected by the gastroenteritis outbreak.

Several athletes have been placed in separate rooms to curtail the outbreak by keeping them away from other athletes for up to 48 hours. The hotel said it was investigating the cause but insisted it was not the source.

Some athletes, including Makwala, who is due to compete in the 400m men’s final tonight, fear they may be forced to withdraw or that the illness will affect their performance.

Makwala's team-mate Lydia Jele told us last night after she competed in the women’s 400m semi-final that he was prevented from running even though his condition is stable now.

Jele said: “He really wanted to run, he was so sad, they didn’t allow him to run the 200m and were saying he should not mix with the other athletes and he should stay for 48 hours in quarantine without competing. Tomorrow it will depend on the officials.”

The Canadian team doctor said nine athletes and staff are also affected by the virus, which causes diarrhoea and vomiting, and that athletes yet to arrive in London will go to another hotel.

A London 2017 Local Organising Committee (LOC) statement said: "There have been a number of cases of gastroenteritis reported by team members residing within one of the official team hotels for the World Championships.

"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.

"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."