The US Department of Justice is investigating alleged violations of competition laws at the PGA Tour.

This follows the Tour's decision not to allow players to jump ship and join the PS200million LIV golf series.

The pressure from Saudi Arabia-backed rebels is a new blow for the golfing authorities.

Greg Norman, leader of LIV, has already pledged to help their golfers with legal action.

Ian Poulter won a temporary injunction last week against the DP World Tour. This overturned their decision to ban Europe-based players and fine them.

Norman was banned sensationally from participating in the 150th Open celebrations at St Andrews.

He was informed that he would not be allowed to attend this week's Champions Dinner or the star-studded four-hole celebration shoot-out at The Old Course.

Norman, who was the Claret Jug winner in 1986 and 1993, was furious at the unimaginable snub. He called it "petty".

The R&A feel Norman's position as the front man for the PS200million Golf Series would be an unwanted distraction and distract from the historic event.

Open organizers issued a statement stating: "In response to inquiries regarding the R&A Celebration of Champions and the Champions' dinner, we can confirm we have contacted Greg Norman to inform him that we did not invite him to this event.

"The 150th Open is a significant milestone in golf. We want to make sure that we keep the spotlight on the Championship and its history.

"Unfortunately, Greg is not able to attend. We hope Greg can attend the next meeting if circumstances permit.

Norman, 67 years old, previously stated that he would attempt to obtain special permission to play at St Andrews. However, this was rejected as a publicity stunt.

Norman won't be the only LIV rebel who will miss the celebrations.

Phil Mickelson, six-time Major champion, was paid an estimated PS150million to sign on for the Saudi Arabia-backed breakaway circuit. He then retaliated by telling the R&A that he wouldn't be available for any of their events.