LONDON — Elite athletes taking part in the International Association of Athletics Federations (IAAF) world track and field championships in the British capital have been struck down by a vomiting bug, British health officials announced Tuesday.

Public Health England said about 30 athletes and support staff reported that they were ill and two of them were confirmed to have norovirus by laboratory tests.

Some German and Canadian athletes staying at the Tower Hotel in the center of London fell ill last week, the BBC reported.

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Among those taken ill were Irish athlete Thomas Barr, who withdrew from the 400m hurdles semi-final, and Botswana’s Isaac Makwala, a favorite for a medal in the 400m, who withdrew from the 200m heats.

“I’m gutted to have to withdraw from today’s semi-final,” Barr said Monday.

“I wasn’t feeling great yesterday evening and later in the night I was hit with a bad bout of gastroenteritis. My whole year has been focused on the World Championships. The support yesterday was just brilliant and to not be able to go out and compete today for Ireland is beyond disappointing.”

“Badnews guys !! Reason for not starting 200m earlier this evening,” Makwala wrote on Facebook. “According to IAAF medics I am apparently suffering from food poisoning which has affected several other athletes in the athletes’ hotel.”

The Tower Hotel said an investigation with health and athletics officials “can confirm that the hotel was not the source of the illness.”

“We have followed strict hygiene protocol, ensuring that those affected are not in contact with other guests and all public areas have been thoroughly sanitised,” it said in a statement.

“We continue to liaise with the medical authorities and the IAAF to ensure the comfort of those guests affected and the health and wellbeing of all our guests remains a priority.”

Deborah Turbitt, London deputy director for health protection at Public Health England (PHE), said: “PHE has been notified of a confirmed outbreak of norovirus among people associated with the World Athletics Championships.

“PHE has been working closely with British Athletics and the hotel to provide infection control advice to limit the spread of illness.”

The IAAF World Champions are taking place from Aug.4-13.