Families of victims of 9/11 told President Joe Biden not to participate in any memorial events for the 20th anniversary of Sept. 11 unless he upholds his promise to declassify U.S. government documents regarding the terrorist attacks.

Nearly 1,800 family members, first responders, and survivors who were directly impacted by the Sept. 11 terror attacks told President Biden he is not welcome to attend any 9/11 ceremonies next month that will mark 20 years since the terrorist attacks that killed nearly 3,000 Americans at the World Trade Center in New York City, the Pentagon, and Shanksville, Pennsylvania.

The 9/11 families will object to "any participation by his administration in any memorial ceremony of 9/11," unless he authorizes the "release of all documents and information to the 9/11 community that our government has accrued in its investigation of the Kingdom of Saudi Arabia (and which former FBI agents have sworn establishes the Kingdom's role in 9/11) to allow us to rightfully obtain justice against the Kingdom."

"As we approach the 20th anniversary of 9/11, and having been used as a political bargaining chip for two decades, our patience has expired," the 9/11 families wrote in a letter to Biden. "We had great hope that President Biden, who campaigned on bringing truth and trust back to the Oval Office, would value the lives and sacrifices of America's citizens over diplomatic relations with a country accused of mass murder."

"We understand President Biden's desire to mark the solemn occasion of the 20th anniversary at Ground Zero," the letter states. "However, we cannot in good faith, and with veneration to those lost, sick, and injured, welcome the president to our hallowed grounds until he fulfills his commitment."

"Since the conclusion of the 9/11 Commission in 2004 much investigative evidence has been uncovered implicating Saudi government officials in supporting the attacks," those directly affected by Sept. 11 wrote. "Through multiple administrations, the Department of Justice and the FBI have actively sought to keep this information secret and prevent the American people from learning the full truth about the 9/11 attacks."

"Twenty years later, there is simply no reason – unmerited claims of 'national security' or otherwise – to keep this information secret," the statement says. "But if President Biden reneges on his commitment and sides with the Saudi government, we would be compelled to publicly stand in objection to any participation by his administration in any memorial ceremony of 9/11, given its continuation of polices that thwart Americans' rights to hold accountable those who, known evidence reveals, materially supported the 9/11 hijackers."

In a campaign promise, Biden vowed to order his Department of Justice to "work constructively" on the 9/11 case, and direct his "Attorney General to personally examine the merits of all cases where the invocation of privilege is recommended, and to err on the side of disclosure in cases where, as here, the events in question occurred two decades or longer ago."

"I intend to be a President for all Americans, and will hear all of their voices," Biden told the families. "The 9/11 Families are right to seek full truth and accountability."

The 9/11 families refer to Biden's promise to authorize the release of documents that detail Saudi Arabia’s role in… https://t.co/4DWlewaTXU

— Patsy Widakuswara (@pwidakuswara) 1628252971.0

Brett Eagleson, who lost his father at the World Trade Center, said he and his co-signers "collectively are at our wits' end with our own government."

"We are frustrated, tired, and saddened with the fact that the U.S. government for 20 years has chosen to keep information about the death of our loved ones behind lock and key," Eagleson told NBC News.

A White House spokesperson said that its Office of Public Engagement and National Security Council staff met with 9/11 victims' family members to discuss their requests for documents and "hear their thoughts on policy priorities," NBC News reported.

The administrations of George W. Bush, Barack Obama, and Donald Trump also declined to declassify 9/11 documents, citing national security concerns.

The 9/11 Commission found no evidence that the Saudi government or senior Saudi officials funded al-Qaeda, but admitted that Saudi government-funded charities could have diverted money to the group.

"The Commission staff found no evidence that the Saudi government as an institution or as individual senior officials knowingly support or supported al Qaeda; however, a lack of awareness of the problem and a failure to conduct oversight over institutions created an environment in which such activity has flourished," the report said.

Several 9/11 families are involved in a lawsuit that accuses Saudi Arabia of being complicit in the Sept. 11 terror attacks.