Snooker world number one John Higgins has reportedly agreed to take a £261,000 bribe to lose frames in four separate matches later this year.
The News of the World says it has video of Higgins and his manager Pat Mooney making a deal in Ukraine on Friday.
Mr Mooney is quoted as saying they feared for their safety at the time. There is no suggestion Higgins has ever thrown a frame or fixed a match.
World Snooker chairman Barry Hearn said an investigation had been launched.
'Massive blow'
He told BBC Radio 5 live he would decide whether to suspend the player within the next 24 hours.
He said he was "absolutely mortified" and the story had come as a "huge shock".
It's really been a shattering experience at this moment in time
Barry Hearn
World Snooker chairman
Mr Mooney is reported to have told the News of the World: "You have no idea what the circumstances were in Kiev, that's why I have no comment.
"But we were genuinely in fear for our safety."
The paper says three-time world champion Higgins refused to comment. Neither Higgins nor Mr Mooney has commented since the publication of the story.
It alleges the sports star inquired at the meeting about the best ways to conceal the 300,000 euros ($398,000) to be received.
In a published transcript, Higgins, 34, from Wishaw, North Lanarkshire, says it would be easy to affect the outcome of a frame so syndicates could place bets.
Many bookmakers now offer the option of betting on individual frames.
Expansion plans
Mr Mooney is a board member of the World Professional Billiards and Snooker Association (WPBSA), whose commercial arm is World Snooker.
Mr Hearn, a promoter, recently proposed an overhaul of the sport including rule changes and boxing-style introductions for the players.
He told the BBC: "I'm absolutely mortified by it [the story]. I've known John Higgins for a long long time.
"Pat Mooney is a co-director of the WPBSA, the governing body of snooker and it's comes as just a huge shock and obviously an enormous blow to the integrity of the sport which is vital as everyone knows for the expansion plans we have.
"So it's really been a shattering experience at this moment in time and one that will be obviously immediately looked into by our disciplinary people under the WPBSA rules."
He said the newspaper allegations had forced him to consider his plans for the sport.
"I want to meet with the players anyway on Wednesday anyway to discuss it. And this is now top of the agenda," he said.
The World Snooker Championship final begins in Sheffield later.
Higgins, who was made an MBE in 2008 and is married with three children, is the current world champion and provisional world number one and has won a total of 21 ranking titles.
He was unexpectedly knocked out of the current tournament in the second round by veteran Steve Davis.