Greg Norman has slammed the "anti-golfer, anti-fan, and anti-competitive" PGA Tour for denying players from entering the opening Saudi-backed LIV Golf Invitational series event next month.

Phil Mickelson, Sergio Garcia and Lee Westwood are among the players who asked to be released to play in the inaugural event at Centurion Club from June 9-11.

The PGA Tour has denied members permission to play in London, as the Canadian Open will be staged at the same time.

"We have notified those who have applied that their request has been declined in accordance with the PGA Tour Tournament Regulations," Tyler Dennis, executive vice president and president of the PGA Tour, wrote in a memo sent to members on Tuesday.

"As such, Tour members are not authorised to participate in the Saudi Golf League's London event under our regulations.

"As a membership organisation, we believe this decision is in the best interest of the Tour and its players."

Norman, the CEO and commissioner of LIV Golf, on Tuesday revealed that the event had secured an additional $2billion in funding ahead and stated that several top players had said they would play without a release.

Norman said in a statement: "Sadly, the PGA Tour seems intent on denying professional golfers their right to play golf, unless it's exclusively in a PGA Tour tournament.

"This is particularly disappointing in light of the Tour's non-profit status, where its mission is purportedly 'to promote the common interests of professional tournament golfers.'

"Instead, the Tour is intent on perpetuating its illegal monopoly of what should be a free and open market.

"The Tour's action is anti-golfer, anti-fan, and anti-competitive. But no matter what obstacles the PGA Tour puts in our way, we will not be stopped. We will continue to give players options that promote the great game of golf globally."