US Senator Richard Blumenthal issued a subpoena Wednesday to a US subsidiary of Saudi Arabia's Public Investment Fund (PIF) to better understand the US PGA Tour-LIV Golf agreement and other investments.

Blumenthal, a Democrat from Connecticut, has demanded documents from PIF's USSA International LLC on the "framework agreement" between PIF and the PGA Tour and other US investments by October 13.

The move comes after PIF has refused to supply the investigation documents or witnesses.

PIF governor Yasir al-Rumayyan, who helped negotiate the golf deal, has refused to testify, representatives saying his Saudi government position prohibits him from testifying on PIF's US business interests.

"PIF's refusal to cooperate is an affront to our authority," said Blumenthal. 

"We can only infer that this means Saudi Arabia intends to gain the benefit of our freedom while avoiding the obligations of our laws."

Blumenthal was troubled by several aspects of billions of dollars of Saudi investments, including "the potential to use investment to suppress unfavorable narratives about Saudi Arabia," including so-called "sportswashing" to deflect Saudi Arabian human rights issues.

"The PIF cannot have it both ways," Blumenthal said. "If it wants to engage with the US commercially, it must be subject to US law and oversight."

There were no representatives from LIV Golf, the PGA Tour or the PIF at a Wednesday hearing into the merger deal, with Blumenthal noting how the stakes are greater than a takeover bid for global golf.

"This inquiry is about much more than the game of golf. It's about more than sports," Blumenthal said. "It's about the need for transparency so Americans can understand when valuable foreign investment becomes a vehicle for malign foreign influence."

The PGA Tour, LIV Golf backers PIF and DP World Tour announced in June a deal to end pro golf's civil war but the "framework agreement" must be completed and approved by the PGA Tour Policy Board by year's end.

That panel now has a majority player representation with Tiger Woods being named to the board in August after many PGA Tour players were unhappy at how the original framework was hammered out in secrecy.

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