Teenage US chess grandmaster Hans Niemann is suing rival Magnus Carlsen for at least $100 million after the Norwegian world champion accused him of cheating.

He has accused Carlsen in a filing of launching a smear campaign in collaboration with Carlsen's online-chess company Play Magnus, and Chess.com, which is purchasing Play Magnus.

Chess.com published a report saying that Niemann had probably cheated in more than 100 online games.

Niemann says that the defendants colluded to destroy his reputation and livelihood, but lawyers for both Magnus Carlsen and Chess.com dismissed the allegations.

Rise 'too rapid'

Carlsen lost to Niemann in an in-person game in September.

The 31-year-old accused Niemann of cheating, and suggested that his rise to prominence in the chess world had been too rapid to be believable.

Niemann said that Carlsen wanted to ruin the teenage player's reputation, and ensure that Niemann would not beat him again.

Neither Carlsen nor Chess.com produced concrete evidence for their cheating accusations.