Veteran US golfer Kevin Na said Saturday he has resigned from the PGA Tour in order to avoid facing sanctions for playing in the Saudi-backed LIV Golf Invitational Series.

The 38-year-old world number 33, who has five victories on the PGA Tour, was this week named in the field for the lucrative new series' opening event teeing off in Britain next week.

Several other golfers including former world number one Dustin Johnson and European Ryder Cup stars such as Ian Poulter and Lee Westwood have also signed up to the event.

The PGA Tour has warned that members playing in the opening LIV tournament – which clashes with the tour's RBC Canadian Open – will face unspecified disciplinary action.

Na said Saturday he was seeking the "freedom to play wherever I want and exercising my right as a free agent gives me that opportunity”.

"However, to remain a PGA Tour player, I must give up my right to make these choices about my career," Na wrote on Twitter.

"If I exercise my right to choose where and when I play golf, then I cannot remain a PGA Tour player without facing disciplinary proceedings and legal action from the PGA Tour.

"I am sad to share that I have chosen to resign from the PGA Tour. This has not been an easy decision and not one taken lightly. I hope the current policies change and I'll be able to play on the PGA Tour again."

Na, who has earned just under $38 million, won the last of his five PGA Tour titles at last year's Sony Open in Hawaii. His best finish in a major came at the 2016 US Open, where he placed seventh.

The money-spinning LIV series is bankrolled by Saudi Arabia's sovereign wealth fund. Amnesty International say the series is an example of Saudi Arabia attempting to "sportswash" its human rights record.