World chess champion Magnus Carlsen publicly accuses rival Hans Niemann of cheating

ITV News reporter Martin Stew explains the controversy

World chess champion Magnus Carlsen has accused rival Hans Niemann of cheating and has vowed to never play against him again.

The Norwegian grandmaster has shared a statement on Twitter claiming the 19-year-old American "cheated more - and more recently - than he has publicly admitted".

Earlier this month Carlsen, 31, played against Niemann at the Sinquefield Cup tournament in St Louis, Missouri, and resigned after his opponent gained the upper hand.

This ended his 53-game unbeaten run in classical chess. Soon after, despite having six rounds left to play, Carlsen withdrew from the competition without providing an explanation.

In what was seen as a veiled swipe against his rival, he posted a tweet including a video showing football manager Jose Mourinho saying: "If I speak, I am in big trouble."

Then last Monday, during the Champions Chess Tour, he resigned against Niemann after playing just one move.

Carlsen is still yet to publicly provide evidence of cheating, but he mentioned Niemann by name in his latest statement posted yesterday.

In it, he writes: "I know that my actions have frustrated many in the chess community. I’m frustrated. I want to play chess. I want to continue to play chess at the highest level in the best events. "I believe that cheating in chess is a big deal and an existential threat to the game.

"I also believe that chess organisers and all those who care about the sanctity of the game we love should seriously consider increasing security measures and methods of cheat detection for over the board chess."

The five-time world champion adds: "I believe that Niemann has cheated more - and more recently - than he has publicly admitted."

Carlsen said his rival's "over the board progress has been unusual" and that during the Sinquefield Cup he had the "impression that he wasn't tense or even fully concentrating on the game in critical positions".

He added that Niemann was outplaying him in black - white pieces having an advantage in chess - "in a way I think only a handful of players can do".

"We must do something about cheating, and for my part going forward, I don’t want to play against people that have cheated repeatedly in the past, because I don’t know what they are capable of doing in the future," said Carlsen.

"There is more that I would like to say. Unfortunately, at this time I am limited in what I can say without explicit permission from Niemann to speak openly.

"So far I have only been able to speak with my actions, and those actions have stated clearly that I am not willing to play chess with Niemann. I hope that the truth on this matter comes out, whatever it may be. "

Niemann has admitted to cheating twice while playing online - once when he was 12 and again when he was 16.

But he has denied ever cheating on the board - meaning during an in-person game - and has accused Carlsen of trying to ruin his career.

"If they want me to strip fully naked, I will do it," said Niemann earlier this month, as he sought to prove his honesty.

He added: "I don't care, because I know I am clean. You want me to play in a closed box with zero electronic transmission, I don't care. I'm here to win and that is my goal regardless."

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In a statement on Friday, International Chess Federation (FIDE) president Arkady Dvorkovich expressed his disappointment at Carlsen's handling of the row.

While the Sinquefield Cup and Champions Chess Tour were not FIDE events, he said that as the sport's worldwide governing body it has a "duty to protect the integrity of the game and its image".

"First of all, we strongly believe that the World Champion has a moral responsibility attached to his status, since he is viewed as a global ambassador of the game," said Dvorkovich.

"His actions impact the reputation of his colleagues, sportive results, and eventually can be damaging to our game. We strongly believe that there were better ways to handle this situation.

"At the same time, we share his deep concerns about the damage that cheating brings to chess. FIDE has led the fight against cheating for many years, and we reiterate our zero-tolerance policy toward cheating in any form."

He said the body is ready to task its Fair Play commission with a thorough investigation when the "adequate initial proof is provided, and all parties involved disclose the information at their disposal".

Dvorkovich added: "It is our hope that this whole situation could have a long-term positive effect, if tackled properly.

"We propose to launch a dedicated Panel, that would include representatives of the leading chess platforms, Grandmasters, anti-cheating experts and FIDE officers, in order to fight this risk and prevent it from becoming a real plague."