Chess superstar Magnus Carlsen for the first time openly accused American Hans Niemann of cheating Monday, saying the rising star had done so more recently and more often than he previously admitted.
The chess world has been shaken for three weeks by the Carlsen-Niemann controversy, since the 31-year-old five-time world champion withdrew from the Sinquefield Cup in the US after losing to Niemann, 19.
Last week, the Norwegian's abrupt withdrawal from a match against Niemann in the Julius Baer Generation Cup online tournament reignited the furore.
In a letter published on Twitter and addressed "Dear 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".