The 13-mile run on Sunday was won by He Jie, a member of China's marathon team and national marathon record holder.

But footage appears to show three runners - Dejene Hailu Bikila from Ethiopia, as well as Robert Keter and Willy Mnangat from Kenya - slow down and let He Jie run ahead of them.

The 25-year-old runner won the half-marathon in a time of 1:03:44, just one second ahead of the trio. All four had run together for the entire race.

Mnangat later told the South China Morning Post he let He Jie win "because he is my friend".

He also added he was not given any financial reward for doing so. He Jie told Chinese state media after the race: "I have never participated in a half marathon before, so this time I wanted to set a personal best."

The event's organiser, the Beijing Sports Competition Management and International Exchange Centre, said it was investigating the incident.

A 'performance'

Some Chinese social media users called the race "embarrassing" or a "performance".

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In a statement, World Athletics told Sky News: "We are aware of the footage circulating online from the Beijing Half Marathon this weekend and understand an investigation is currently being conducted by the relevant local authorities.

"The integrity of our sport is the highest priority at World Athletics, while this investigation is ongoing we are unable to provide further comment."

Distance running events in China have been marked by controversy in the past: In a 2018 half marathon in Shenzhen, 258 runners were seen cheating and taking shortcuts.

In 2021, 21 runners died during a mountain marathon cross-country race in northwest China over extreme weather.