It was updated Sept 26, 2022, 05:53pm.

After weeks of speculation among the chess community, reigning world chess champion Magnus Carlsen accused grandmaster Hans Niemann of cheating in a statement released Monday.

Tata Steel Chess Tournament 2021

Magnus Carlsen of Norway is competing in the chess tournament.

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Carlsen, who previously only addressed the cheating allegations in cryptic social media posts, said Monday in a statement that he has cheated more recently than he has admitted.

During their match at the Sinquefield Cup earlier this month, which Carlsen lost in a shocking upset, Carlsen said that Niemann was not tense or fully concentrating during critical moments of the game.

Carlsen said that cheating in chess is a big deal and a threat to the game.

Carlsen is limited in what he can say publicly because he doesn't have permission to speak to the public.

Forbes asked for comment from Niemann, but he did not reply.

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Chess fans have speculated about how Niemann could have cheated. The alleged leak of Carlsen's opening move preparation was denied by Niemann, who said he guessed Carlsen's first move "by some ridiculous miracle." One theory is that a small vibrating device may have been hidden on his person to communicate with a third party.

In the third round of the Sinquefield Cup in St. Louis, Carlsen was defeated by the lowest ranked player in the tournament. Carlsen withdrew from the tournament after the loss and shared a video online of Portuguese soccer coach Jose Mourinho saying, "If I speak, I am in big trouble" The video was seen by many in the chess world as a cheat accusation. There was a lot of tension last week when Carlsen and Niemann went head-to-head in a preliminary game for the Julius Baer Generation Cup. Carlsen resigned after just one move. Since the Sinquefield Cup, Niemann has admitted to cheating online, but denied wrongdoing in his game with Carlsen. Chess.com, the world's largest online chess platform, removed Niemann after uncovering evidence that contradicted his statements about the severity of his cheating.

Magnus Carlsen quit the match after just one move against the other player.