Chess World Champion Magnus Carlsen accuses Hans Niemann of cheating

World Chess Champion Magnus Carlsen publicly accused American chess player Hans Niemann of cheating on Monday, alleging that Niemann had done it more recently and more frequently than he had previously acknowledged.

Since, Carlsen withdrew from the Sinquefield Cup in the US after losing to Niemann, three weeks ago, the Carlsen-Niemann issue has rocked the chess world.

The controversy was renewed last week when the Norwegian abruptly withdrew from a match versus Niemann in the Julius Baer Generation Cup online competition.

In a statement on the social media network, Twitter addressed to Chess World, Carlsen said, "I believe that Niemann has cheated more -- and more recently -- than he has publicly admitted. His over-the-board progress has been unusual."

He did not specify the exact form of the alleged cheating, but added there was "more that I would like to say".

Carlsen said, "I know that my actions have frustrated many in the chess community. I am frustrated. I want to play chess. I want to continue to play chess at the highest level in the best events."

He said cheating in chess was "an existential threat to the game" and said: "I don't want to play against people that have cheated repeatedly in the past."

Niemann has admitted to cheating twice online, once when he was 12 and once when he was 16, but he claims he has never played dishonestly in a face-to-face encounter and is even willing to play in the naked state to demonstrate his sincerity.

The American was banned from the popular chess website chess.com in early September because of website cheating.