NEW YORK — A federal judge has ordered lawyers for 9/11 families suing Saudi Arabia to detail threats allegedly made against witnesses they may depose as part of their effort to prove the kingdom was involved in the 2001 terrorist attacks.

The victims' attorneys have argued they need to protect for now the identities of potential witnesses, pointing to the murder of journalist Jamal Khashoggi as an example of the kind of danger faced by those who speak out against Saudi Arabia. Khashoggi, a contributing Washington Post columnist and outspoken critic of the Saudi crown prince, had been interviewed by an investigator for the plaintiffs in 2017.

Lawyers for those suing Saudi Arabia — including survivors of the attacks and victims’ relatives — said at an emergency court hearing Wednesday that the October 2018 killing of Khashoggi at the Saudi Consulate in Istanbul has heightened their concern for four potential witnesses. Those people, the lawyers said, have been in talks with the families about providing information on Saudi Arabia’s alleged role in the Sept. 11, 2001, attacks on New York and Washington.

U.S. Magistrate Judge Sarah Netburn said she was “troubled by the allegations” that witnesses were threatened and asked for a submission from the plaintiffs’ lawyers “documenting in greater detail the information that you have” by March 18. Netburn gave the attorneys permission to redact the names of the witnesses. The submission will initially be filed under seal and will not be available to the Saudi government’s legal team, the judge ruled.

The issue of safety came up amid legal jousting over whether the identities of potential witnesses should be turned over to the Saudis’ legal team. The plaintiffs argued it was premature to turn over such information because it’s still unclear which of the potential witnesses will be deposed and testify.

Attorney Andrew Maloney, a former federal prosecutor in the Southern District of New York, where the 9/11 case is pending, laid out in a previous court filing what he described as a pattern of harassment and threats against witnesses. He said the targeted individuals had reported the incidents to police or planned to do so.

Maloney wrote in a Feb. 21 declaration that he has “spoken with several third party witnesses with personal knowledge relevant to the 9/11 terror litigation who have expressed to me their fears of testifying against the Saudi government.”

One witness “had been approached in person and directly threatened by Saudi government officials” or their employees or agents, Maloney wrote, adding that the person or their family were told they could be murdered.

Another witness said they believed they were stalked by “Saudi agents” after their name appeared in a court document and that the person feared they could be made to “disappear,” the attorney wrote.

Maloney said the incidents amounted to witness tampering.

Michael Kellogg, who represents Saudi Arabia, said Maloney’s allegations are “based on hearsay within hearsay.”

In court papers, a Saudi government minister said “[no] Saudi Arabian government official, employee, agent, or anyone acting on Saudi Arabia’s behalf has attempted to threaten any potential witness or any witness’s family members in this proceeding.”

Charles Wolf, a plaintiff whose wife was killed in the World Trade Center attack, said the allegations of witness intimidation are shocking and credible.

“If anything, the Saudi government is keeping [its lawyers] in the dark,” he said.