LONDON • The IAAF World Championships descended into chaos on Tuesday after the organisers refused Isaac Makwala permission to enter the London Stadium for the 400m final despite the runner insisting that he was fit to race.

The Botswanan claimed that the decision to rule him out on medical grounds was "sabotage".

And American Michael Johnson, the former 200m and 400m record-holder-turned-BBC analyst, said that Makwala's absence could have been a way of making it easier for the South African Wayde van Niekerk to win gold.

Makwala had been pulled from his 200m heats on Monday after reports that he had vomited, amid fears that he had fallen victim to the norovirus outbreak at the team hotel. It was then announced that he would be barred from taking his place in the 400m final as he had to be quarantined to avoid spreading the virus.

Yet Makwala, who is ranked No. 3 in the world over 400m this year behind van Niekerk and American Fred Kerley, ignored the order and turned up at the stadium demanding to race. When he arrived at the warm-up track he was met by IAAF officials and security staff, who refused to let him enter.

The runner, who had been among the pre-event favourites for the 200m, insisted that he was not sick and told officials he had a medical certificate stating that.

"I am heartbroken," said the 30-year-old. "I have waited. I feel like it is sabotage. I'm not sure if it is the IAAF or the British. I am feeling good to run tonight."

Lane seven, in which he was to run, was vacant for the race, which was won by van Niekerk. The 25-year-old comfortably won in 43.98 seconds.

Steven Gardiner of the Bahamas claimed silver in 44.41sec, with Sudan-born Qatari Abdalelah Haroun taking bronze (44.48sec).

Van Niekerk's bid for a first world double since 1995 now turns to the 200m, in which neither Usain Bolt nor the world's fastest man this season, Makwala, are running.

The last athlete to claim the 200-400m double was Johnson, who stirred the pot on television, saying that the IAAF "had got it horribly wrong".

He also said that some had claimed that the decision was made to give an easy ride to van Niekerk, who broke Johnson's 17-year world record in the 400m at the Olympic Games in Rio de Janeiro last year.

"The elephant in the room is that Wayde van Niekerk is an IAAF favourite, a fan favourite, he's a favourite of everyone," the 49-year-old said. "He's the world-record holder, champion, the Olympic champion. And now the only person who was his challenge, Isaac Makwala - who was going to double as well, who has the fastest time in the world this year, 19.74 for 200m, and the second-fastest time in the world this year for 400m - has been pulled out of both these races. Conspiracy theories are going round."

The race was a flat and one-sided contest, with van Niekerk barely celebrating his victory, instead easing up a full 15m from the line.

"As much as we want to win gold medals, we also want to go out there and have best guys on the track with us," van Niekerk said. "It's such a massive pity. (Makwala's) a strong athlete, I've seen him break through a lot of challenges. So I have a lot of sympathy for him. I wish I could give him my medal to be honest."

The IAAF issued a statement regretting that Makwala did not race.

"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," it said.

The championships have been hit by more than 30 cases of gastroenteritis, particularly to Canadian and German athletes.

THE TIMES, LONDON, AGENCE FRANCE-PRESSE, REUTERS

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