The International Chess Federation (FIDE) said it will convene a three-person panel to look into world champion Magnus Carlsen's allegations that American player Hans Niemann had cheated.
Carlsen, 31, withdrew from the Sinquefield Cup in St Louis, Missouri, earlier this month after losing to the 19-year-old, who lags him by almost 200 Elo points - the rating system used to calculate the relative skill level of players.
The surprise defeat and Carlsen's withdrawal from the over-the-board tournament sparked a furore of comments and allegations that Niemann had cheated, including from US Grandmaster Hikaru Nakamura.
The Norwegian then resigned at the Julius Baer Generation Cup after just one move against Niemann in an online game.
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. However, he has denied any wrongdoing in over-the-board games.
Carlsen on Monday said that he believed Niemann had "cheated more - and more recently - than he has publicly admitted".
FIDE said in a statement on Thursday: "The focus of the investigation would be twofold: checking the world champion's claims of alleged cheating by Niemann and Niemann's self-statement regarding online cheating.
"The panel will ensure a fair ruling, protecting the rights of both parties during the investigation."