The IAAF has come under criticism after the exclusion of Botswana medal hope Isaac Makwala from Tuesday night's 400 metres final at the World Athletics Championships.

Makwala was not allowed to compete on medical grounds following a bout of norovirus.

The 30-year-old had been expected to challenge favourite and Olympic champion Wayde van Niekerk, who went on to comfortably defend his world title at the London Stadium.

Video footage showed Makwala was prevented from entering the warm-up track and Botswanan officials criticised the IAAF for their heavy-handedness and lack of communication.

Stomach bugs have affected several athletes in London, including Ireland’s 400m hurdles champion Tom Barr who was forced to pull out before his semi-final.

Makwala told ITV News: "They said I had food poisoning - which I don't have. I was not tested for that.

"They didn't even want to listen to me. They said 'no, you can't run because you are sick.' Sometimes I think maybe this is sabotage."

Athletics' world governing body defended its decision, saying it was taken to contain the contagious illness.

The IAAF said in a statement issued moments before the final: "The IAAF is very sorry that the hard work and talent of Isaac Makwala won't be on display tonight but we have to think of the welfare of all athletes.

"The athlete was diagnosed with an infectious disease on Monday."

Wayde van Niekerk runs to 400m victory in London

The statement continued: "As per UK health regulations, it was requested that he be quarantined in his room for 48 hours, a period which ends at 1400hrs tomorrow (August 9).

"These procedures are recommended by Public Health England and were clearly explained to the teams in writing on Sunday (August 6) and in person to the Botswanan delegation, a member of which was present with many other representatives of teams at a meeting that took place at the Guoman Tower Hotel on Sunday."

Botswana team officials dispute the IAAF's version of events, and national sports commission chief executive Falcon Sedimo said the team found out about Makwala's exclusion through the media.

Makwala had been given medical dispensation to withdraw from the 200m heats on Monday night.

Without a valid reason for pulling out, he could have been disqualified from the 400m final - an event he was forced to miss.

Former 400m world and Olympic champion and world record holder Michael Johnson questioned the decision.

Johnson told the BBC: "There is the elephant in the room - Wayde van Niekerk's only challenger has been pulled out of both the 200m and 400m. The conspiracy theories will come out of the silence."