(CNN) A coalition of families and survivors of the 9/11 terrorist attacks says it will protest at the "front door" of Augusta National Golf Club if the institution doesn't reconsider its decision to invite golfers who have played in the Saudi-backed LIV Golf series to the Masters in April.
A number of golfers who played in the LIV Golf tour have been invited, including World No.3 Cam Smith, Bryson DeChambeau and Phil Mickelson, one of six former Masters champions to have competed on the controversial tour.
"In the aftermath of 9/11, our country agreed we would 'Never Forget' that horrible day," 9/11 Families United said in a press release Tuesday.
"The only reason the Saudis launched LIV was to try to make the world forget who they are and what they did, including their role in 9/11. Anyone who truly vowed to 'never forget' should be appalled by the decision by these golfers to put money ahead of their own country.
"On behalf of 9/11 Families United, we are calling on Augusta National to reconsider their open-door policy to the LIV golfers. If they are welcomed with open arms, we will be at their front door to protest in April."
Augusta National's spokeswoman didn't immediately respond to CNN's request for comment.
Fifteen of the 19 al Qaeda terrorists who hijacked four planes on September 11, 2001 were Saudi nationals, but the Saudi government has long denied any involvement in the attacks.
In 2004, the 9/11 Commission established by Congress said it had found "no evidence that the Saudi government as an institution or senior Saudi officials individually funded" al Qaeda.
Still, the victims' families have pushed for further disclosures, and last year the FBI released a document that details the agency's work to investigate the alleged logistical support that a Saudi consular official and a suspected Saudi intelligence agent in Los Angeles provided to at least two hijackers.
Ahead of LIV Golf's maiden event in London in June, Terry Strada, the National Chair of 9/11 Families United, called on Mickelson, DeChambeau, Dustin Johnson, Patrick Reed and Kevin Na to renounce their participation in the event. All six golfers are invited to the Masters in April.
In June, Mickelson said he had "deep empathy" for the victims of the 9/11 terror attacks.
"I would say to the Strada family, I would say to everyone that has lost loved ones, lost friends on 9/11 that I have deep, deep empathy for them. I can't emphasize that enough," the six-time major winner said when questioned by reporters during a news conference.
"I have the deepest of sympathy and empathy for them."
At the time, Strada, whose husband Tom died in the collapse of the World Trade Center's North Tower said Mickelson "knows exactly what he's doing."
"He and his fellow LIV golfers should be ashamed."
The LIV Golf series is backed by Saudi Arabia's Public Investment Fund (PIF) -- a sovereign wealth fund chaired by Mohammed bin Salman, the Crown Prince of Saudi Arabia.