Poulter is among 11 LIV Golf players who have taken legal action in the US to get their suspension from the North American golf tour lifted.

LIV Golf has caused fractures across the golf world since attracting players with signing-on fees reportedly exceeding £100m in some cases, and a $25m (£20.6m) prize fund per event.

In a memo to members obtained by Sky News, PGA Tour commissioner Jay Monahan wrote: "With the Saudi golf league on hiatus, they're trying to use lawyers to force their way into competition alongside our members in good standing. It's an attempt to use the Tour platform to promote themselves and to freeride on your benefits and efforts.

"To allow re-entry into our events compromises the Tour and the competition, to the detriment of our organisation, our players, our partners and our fans. The lawsuit they have filed somehow expects us to believe the opposite, which is why we intend to make our case clearly and vigorously."

The series is being bankrolled by Saudi Arabia's sovereign wealth fund, sparking criticism from activists who accuse the kingdom of using the glamour of sport to enhance the kingdom's image while concerns persist about violations of human rights.

Players signed up to start competing on the LIV Golf circuit in June despite the threat of PGA Tour disciplinary action for a year.

A temporary restraining order has been sought by a trio of players - Talor Gooch, Hudson Swafford and Matt Jones - to compete from next week in the FedEx Cup play-offs which determine the season champion on the PGA Tour.

Mr Monahan said: "We have been preparing to protect our membership and contest this latest attempt to disrupt our Tour, and you should be confident in the legal merits of our position. Fundamentally, these suspended players - who are now Saudi Golf League employees - have walked away from the Tour and now want back in."

Read more:
Why LIV Golf is the most controversial tournament in sport
Phil Mickelson says he doesn't condone human rights abuse ahead of Saudi-backed tour

There is a month until the next LIV Golf event in Boston.

The antitrust lawsuit against the PGA Tour was filed in the US District Court in San Francisco.

LIV Golf said in a statement: "The players are right to have brought this action to challenge the PGA Tour's anti-competitive rules and to vindicate their rights as independent contractors to play where and when they choose. Despite the PGA Tour's effort to stifle competition, we think golfers should be allowed to play golf."

Mr Monahan said he is defending the rights of members who abide by the rules and urged players to speak out against LIV Golf.

He added: "This is your TOUR, built on the foundation that we work together for the good and growth of the organisation…and then you reap the rewards. It seems your former colleagues have forgotten one important aspect of that equation."