World chess champion Magnus Carlsen has accused fellow player Hans Niemann of cheating and said he will never play against him again.
Carlsen said he believed the American teenager had “cheated more – and more recently – than he has publicly admitted”.
The 31-year-old Norwegian said he no longer wanted to play against the 19-year-old – and any other rivals who have repeatedly cheated in the past.
Carlsen, world champion since 2013, resigned from an online match via video link against Niemann last week after making only one move.
The two players were competing in the Julius Baer Generation Cup – their first meeting since Niemann’s victory over Carlsen at the Sinquefield Cup earlier this month.
Carlsen also withdrew from the Sinquefield Cup in St Louis, Missouri, following the unexpected defeat – which triggered the fallout and allegations Niemann had cheated.
It ended Carlsen’s 53-game unbeaten run in classical chess.
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Niemann, who lags Carlsen by almost 200 Elo points – the rating system used to calculate the relative skill levels of players – has denied any wrongdoing.
“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,” Carlsen said in a statement on Twitter on Monday.
“When Niemann was invited last minute to the 2022 Sinquefield Cup, I strongly considered withdrawing prior to the event. I ultimately chose to play,” Carlsen said.
Niemann, has previously been banned from chess.com for cheating online after admitting he had not played fairly in non-competitive games on the website in his youth.
“I believe that Niemann has cheated more – and more recently – than he has publicly admitted,” Carlsen said.
“His over the board progress has been unusual, and throughout our game in the Sinquefield Cup I had the impression that he wasn’t tense or even fully concentrating on the game in critical positions, while outplaying me as black in a way I think only a handful of players can do.”
He continued: “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.”
Carlsen made a plea for stricter detection measures while repeating his concerns about cheating in the sport.
“I hope the truth on this matter comes out, whatever it may be,” he added.
Niemann said recently when the controversy began: “I have never cheated in an over the board game.
“If they want me to strip fully naked, I will do it. I don’t care. Because I know I am clean.”
Over the board means playing face to face with another person and physical chess pieces, rather than electronically.
