CNN  — 

Hours after the LIV Golf Invitational Series announced the field for its inaugural event next week, the PGA Tour threatened “disciplinary action” for PGA Tour golfers who participate in the new Saudi-backed series.

In a strong rebuttal to the controversial new golf tour, the PGA Tour said on Wednesday: “As communicated to our entire membership on May 10, PGA TOUR members have not been authorized to participate in the Saudi Golf League’s London event, under PGA TOUR Tournament Regulations.

“Members who violate the Tournament Regulations are subject to disciplinary action.”

Two-time major winner Dustin Johnson will be the headline act at the inaugural LIV Golf Invitational Series event, which hosts its first event from June 9-11 at the Centurion Club outside London.

Johnson, currently the world No. 13, will be the highest-ranked player at the tournament, which will also include Sergio Garcia, Lee Westwood, Ian Poulter, Martin Kaymer, Kevin Na, Louis Oosthuizen and Branden Grace.

As recently as February, Johnson said that he was “fully committed to the PGA Tour.”

Six-time major winner Phil Mickelson, an outspoken supporter of the new tour, does not feature in the field at the Centurion Club.

The 51-year-old said in February he would take “some time away” from golf after being criticized for comments he made about Saudi Arabia’s regime and the country’s new tour.

READ: ‘We’ve all made mistakes,’ says Greg Norman of Saudi journalist Jamal Khashoggi’s murder

Dustin Johnson will be the star name in the field at the Centurion Club.

“Free agency has finally come to golf,” Greg Norman, LIV Golf CEO and Commissioner, said in a statement. “This is an opportunity to start a movement that will change the course of history by bringing new and open competition to the sport we all love.

“The desire shown by the players to participate in LIV Golf demonstrates their emphatic belief in our model and confidence in what we’re building for the future.”

Norman received fierce criticism last month for appearing to downplay the the murder of Saudi journalist Jamal Khashoggi ahead of the tour’s launch, saying: “We’ve all made mistakes.”

A US intelligence report named Mohammed bin Salman, the Crown Prince of Saudi Arabia, as responsible for approving the operation that led to the 2018 murder of Khashoggi – something bin Salman denies.

The Centurion Club tournament will have a total prize pot of £20 million ($25.2M), with £3 million ($3.8M) for the winning golfer. Six places still remain open in the 48-man field.

The event takes place at the same time as the PGA Tour’s Canadian Open, which Johnson had been scheduled to compete in.

In a statement posted on Twitter, the Canadian Open, a tournament Johnson won in 2018, said it was “disappointed” with the two-time major winner’s decision to opt to play in the Saudi-backed event.

“As a past RBC Canadian Open champion, Canadian golf fans were looking forward to DJ’s return this year,” it said.

“Our focus continues to be on hosting the widely celebrated return of the RBC Canadian Open and welcoming the world’s best players to Canada.”

The PGA Tour has not granted permission for its players to compete elsewhere and they could reportedly be set to face punishment for their decision.

“Dustin has been contemplating the opportunity off-and-on for the past couple of years,” David Winkle at Hambric Sports Management said in a statement on behalf of Johnson.

“Ultimately, he decided it was in his and his family’s best interest to pursue it. Dustin has never had any issue with the PGA TOUR and is grateful for all it has given him, but in the end, felt this was too compelling to pass up.”

In a statement sent to CNN, Royal Bank of Canada said it is terminating its sponsorship agreements with Johnson and Graeme McDowell, who has also signed up for the LIV Golf series.

Meanwhile Rory McIlroy said that PGA Tour should not “drop the hammer” on any golfers that have decided to participate in the upcoming event.

“A couple – a couple of surprises in there I think … they [PGA Tour] are well within their rights to enforce the rules and regulations that have been set,” PGA Tour star McIlroy told reporters before the Memorial Tournament on Wednesday.

“It’s going to end up being an argument about what those rules and regulations are.

“It’s not something that I would do personally. But I certainly understand why some of the guys have went, and it’s something that we are all just going to keep an eye on and see what happens over these next few weeks,” added McIlroy.

“But I certainly don’t think the field is anything to jump up and down about.”

CNN’s Jacob Lev contributed to reporting.