NEW YORK — Federal prosecutors have asked a judge to appoint a "special master" to review material seized by the FBI last week from Rudy Giuliani and ensure investigators aren't able to see records protected by attorney-client privilege, according to court records unsealed Tuesday.

In a letter dated Thursday, prosecutors requested the oversight, partially citing Giuliani's work as a lawyer for former President Donald Trump.

They noted it would be similar to what occurred after federal agents seized electronic devices three years ago from the home and office of Michael Cohen, who was also one of Trump's lawyers.

Cohen eventually pleaded guilty to campaign finance law violations  and other crimes and was sentenced to three years in prison. After about a year in prison, he was released to home confinement as the threat of the coronavirus led to early release for some non-violent prisoners.

The federal probe is examining Giuliani's interactions with Ukrainian figures and whether he violated a federal law that governs lobbying on behalf of foreign countries or entities.

Giuliani, a Republican and former mayor of New York City, has not been charged with a crime. He has said all of his activities in Ukraine were conducted on behalf of Trump. At the time, Giuliani was leading a campaign to press Ukraine for an investigation into Joe Biden and his son, Hunter, before Biden was elected president.

Last Wednesday, FBI agents recovered multiple electronic devices during an early-morning search of Giuliani's home and office.

In their letter, prosecutors said the search was carried out on Giuliani by FBI agents who have not been involved in the investigation and will not be involved in the future.

They said in the letter to U.S. District Judge J. Paul Oetken a day after the searches that FBI technical specialists had begun extracting materials from the seized devices, but had not yet begun reviewing the materials.

Oetken permitted some redactions prior to the unsealing of the government's letter, including portions specifying what was taken from Giuliani and Washington lawyer Victoria Toensing, a former federal prosecutor and close ally of Giuliani and Trump. Her law firm said after the searches that she was told she was not a target of the investigation.

Oetken set up a schedule for filings pertaining to legal issues starting next week.

Giuliani has objected to the seizure in part because he contends the material on the devices would be subject to attorney-client privilege — the client being Trump. Courts sometimes designate an attorney not directly involved with the case, known as a special master, to address such concerns.

In more ordinary cases, a review of material seized from a lawyer might be conducted by a government "filter team" or a magistrate judge.

But they wrote that the government considered it appropriate to appoint an outside master in the Giuliani probe to determine what must be protected by attorney-client privilege in part because of "the overt and public nature of these warrants."

They then quoted Judge Kimba Wood from the Cohen case when she stated that a master was appropriate for the "perception of fairness, not fairness itself." Wood appointed a former Manhattan federal judge to conduct the oversight.

Citing a terrorist probe of a lawyer 20 years ago, prosecutors said a government "taint team" was commonly used but added that the appointment of a master may be appropriate when the attorney represents the U.S. president.

A lawyer for Giuliani did not immediately return a request for comment Tuesday. A spokesperson for prosecutors declined comment.