A proposal to allow Israeli security agents to use “light disguise” while testifying in an American court is under fire from a left-leaning civil liberties organization, the Center for Constitutional Rights.

Muhammad Salah, 53, of Bridgeview, Ill., and Abdelhaleem Ashqar, 48, of Alexandria, Va., are scheduled to go on trial in October on charges they funneled money to the terrorist group that won Palestinian Authority elections in January, Hamas.

Last month, federal prosecutors asked that the courtroom be closed to the public when Israeli agents are called as witnesses, and to wear glasses or facial hair not part of their normal appearance. The prosecution also urged the judge to keep secret the names of jurors seated for the trial.

On Monday, a coalition of groups represented by the Center for Constitutional Rights asked to intervene in the case, arguing that the proposed security measures are unconstitutional.

“These Israeli agents, who supposedly need to testify and can’t be seen, they’ve interrogated hundreds of Palestinians without disguises,” a Chicago attorney working with the civil liberties group, Steven Saltzman, said in an interview. “I don’t think there’s much question that people know what they look like.”

Prosecutors have argued that the security measures are needed to protect the witnesses’ safety and to prevent Hamas from attacking jurors. “The international reach and operation of the Hamas organization suggest that it has the capacity to harm jurors,” prosecutors wrote in court filing. They acknowledged that, thus far, Hamas has confined its attacks to Israel, Gaza, and the West Bank, but said Hamas has killed Americans and made threats against American interests.

Mr. Saltzman said keeping jurors’ identities secret would undermine the presumption of innocence. “An anonymous jury says to people that the defendant is a dangerous guy,” the lawyer said.

Prosecutors have asked Judge Amy St. Eve to close the courtroom during the testimony by Israeli agents and to provide an audio feed to observers in another room.

The defendants, who pleaded not guilty and denied being members of Hamas, also are opposing the unusual government requests.

Much of the testimony by Israeli agents is expected to relate to Mr. Salah’s interrogation while in detention in Israel in 1993. In an unusual twist, a former reporter for the New York Times, Judith Miller, was present at one of those sessions and directed questions to Mr. Salah through an Israeli interrogator, according to court papers and a book written by Ms. Miller.

It is unclear whether Ms. Miller, who spent 85 days in jail last year for refusing to identify a source as part of a CIA leak investigation, will be called as a witness at the upcoming trial.

The challenge to the government’s trial proposals was joined by several Islamic and human rights organizations, which noted Mr. Salah’s claims that he was tortured while in Israeli custody. Israeli agents have denied mistreating him.

“There are certainly individuals and organizations within the group who believe he was tortured, but we haven’t taken a position on that in terms of the court filings,” Mr. Saltzman said.