The chess cheating scandal became a raging storm today as Magnus Carlsen threw his hotly-anticipated rematch with Hans Niemann in the Julius Baer Generation Cup.

With the chess world watching on, Carlsen played one move with Black and then sensationally resigned in the Round 6 clash. He then got up, turned off the camera and left the broadcast.

Norway's World Champion made no comment afterwards, but it was presumed he did it in protest.

The game went 1. d4 Nf6 2. c4 before Carlsen ended it.

The reaction was swift and strong. In the commentary box, International Master Jovanka Houska accused Carlsen of "pouring more fuel on the fire" of a controversy that has rocked chess since the 31-year-old withdrew from the Sinquefield Cup two weeks ago.

International Master Jovanka Houska

Clearly shocked, IM Houska said Carlsen "can't just do this" and called for him to present his evidence.

"Actually, I think he needs to do more than just a statement in fact," she said. "He can't just say, 'yeah, I think you cheated' and initiate a witch-hunt. He has to say, 'this is my proof'."

Grandmaster Peter Leko was also "speechless".

Carlsen has not publicly accused Niemann of cheating, but shocked the chess world when he withdrew from the Sinquefield Cup in St Louis the day after losing to him. It was the first time in his career Carlsen had done so.

Intentionally or not, Carlsen then set rumours swirling when he tweeted a cryptic message on Twitter. It featured a clip of football manager Jose Mourinho saying, "I prefer not to speak. If I speak I am in big trouble".

Following a wave of criticism, including from some top grandmasters, Niemann vociferously denied any form of cheating during the event, although he admitted he had previously cheated online.

Carlsen, meanwhile, has gone silent on social media.

However, both players were invited to take part in the Meltwater Champions Chess Tour's Julius Baer Generation Cup, and accepted.

So far Carlsen has remained silent, refusing post-match interviews during the $150,000 event. His father Henrik also told the Norwegian channel TV 2 today that he won't be interviewed for the duration.

Alejandro Ramírez, the grandmaster who interviewed Niemann after the Sinquefield Cup, told the Tour broadcast that "something is up".

Speaking from the Dominican Republic, he said: "It's a clear indication that Magnus thinks that something is wrong, with Hans.

"Whether it's cheating, whether it's something else that happened, there are other possibilities. The word cheat gets used a lot, but there's a lot of other things that may have happened.

"I don't know what it is, but I do know that this is so strong that Magnus needs to come forward and say something."

Grandmaster David Howell said: "This is unprecedented in the history I think by any World Champion, by any top player, let alone Magnus, who loves playing any game possible and has great respect for the game of chess and every tournament he plays.

"It's just bizarre, bizarre times."

He added: "You can't just leave it on this note. I don't know if he can continue the tournament if he leaves it on this note. I just wish we'd seen a game, that's all I can say."

Grandmaster Simon Williams said: "One thing that comes out of this is that it needs to be clarified. You can't make wild accusations. Imagine doing that in a court of law, you've got to be innocent until proven guilty, that is just a fact."

On live Norwegian TV, Grandmaster Jon Ludvig Hammer, team mate and former World Championship assistant, called for sanctions.

"It's the most unacceptable behavior to lose on purpose," he said. "The most unsportsmanlike thing you can do."

Prof Ken Regan

Asked what he thought, Professor Ken Regan, considered the authority on cheat detection in the chess world, said: "Very much regret, it's not proper.

"One thing about the tournament is that the top eight qualify, and I guess Magnus feels like to be near the top of those top eight.

"But now he has gifted Hans Niemann a free point and if that causes Niemann to go in when someone else would have that other person has a complaint. So it's very unfortunate for the sporting nature."

Speaking after his Round 8 game ended, Levon Aronian appeared to suggest Carlsen has a case.

Levon Aronian speaking on the chess24 broadcast

He said: "I understand that frustration of Magnus. I really didn't know much about a lot of things.

"Now I am somewhere in the middle. I do believe Hans has not been the cleanest person when it comes to online chess.

"But he's a young guy, hopefully this will be a lesson to him not to do any bad things online. Generally, I think this is a problem that requires a solution - and there are solutions."

Following his early exit, Carlsen maintained focus with a Round 7 win over Aronian.

"It was just a really, really strong game there by Magnus Carlsen in the circumstances," GM Howell said.

Carlsen applauds Pragg

In the final round the world number one found himself up against his teen tormentor Rameshbabu Praggnanandhaa, who had beaten him three times on the Tour already this season.

Pragg went for the throat but a fiesty game ended in a draw. Carlsen applauded his young opponent and ended the day on 15/24, two points behind tournament leader Arjun Erigaisi.