Mr Mizuhara had been a constant companion of the extremely private Ohtani for much of the player’s illustrious career. He was seen carrying out food shopping for Ohtani when he was injured, and they typically drove to the ballpark together.

The Dodgers terminated Mr Mizuhara after a game last Wednesday, ending a partnership with Ohtani that began in 2013.

MLB said on Friday that it was formally investigating the allegations against him.

Baseball players are banned from betting on baseball in any form or at any level, including in the form of fantasy sports. Sports betting is illegal in California, where Ohtani has played his entire Major League (MLB) career. Offshore sports betting operates in murky waters and does not require upfront payments, relying instead on credit.

The controversy surrounding MLB and Ohtani has prompted a reexamination of the relationship between sports and the gambling industry – a long standing controversial issue in the US.

Until 2018, sports betting was illegal nationwide, but it has grown into a $10 billion industry in just six years. A total of 38 states now allow spectators to follow the odds, and betting advertisements, once banned, are becoming increasingly common during games.

The day before the scandal involving Ohtani and his assistant broke, the NBA said it would integrate betting into live games on NBA League Pass, which streams basketball games live to subscribers.

The new system will allow viewers to track betting odds on games as they watch them via the app and then click through to wager on the NBA’s betting partners.

Last year, MLB and online gambling giant FanDuel announced a partnership that allows fans to watch games and place bets at the same time through FanDuel’s app.

The broadcaster ESPN has its own sportsbook, ESPN Bet, linked to from its homepage.

Commentators in the US have questioned the integrity of sports leagues for embracing the gambling industry.