The US PGA Tour is suing Saudi Arabia's Public Investment Fund and its governor Yasir Othman Al-Rumayyan in the latest legal salvo against the Saudi-backed LIV Golf Series.The complaint was filed under seal in US District Court for the Southern District of New York on Thursday, according to court records.ESPN, citing unnamed sources, reported on Friday that the lawsuit seeks to have a court compel Al-Rumayyan and the PIF to provide evidence in an ongoing lawsuit in California involving the warring golf circuits.The sports website said the suit seeks a motion to compel that would require the PIF to release documents to PGA Tour lawyers through the legal discovery process.Sunshine Tour | Talented youngster Naidoo claims first Sunshine Tour title with SunBet victoryThe sovereign wealth fund of Saudi Arabia, PIF created a division called Golf Saudi which has backed a number of events in the sport before the creation of LIV.PIF are also majority owners of Premier League club Newcastle United after completing a takeover last year.The suit also requires Al-Rumayyan, who is also chairman of Newcastle and the Saudi Aramco oil company, to give sworn testimony.The launch this year of LIV Golf, which has lured some top players with record purses, has polarized golf and drawn a swift response from the established PGA and DP World Tours.The PGA Tour has banned more than 30 players who have teed off in one of LIV's 48-man, 54-hole tournaments, a move that prompted 11 LIV Golf players to file an anti-trust lawsuit against the PGA Tour in August.Eight of the original plaintiffs in that suit, including vocal LIV supporter Phil Mickelson, have since removed their names from the action, while Bryson DeChambeau, Matt Jones and Peter Uihlein