UPPER EAST SIDE, Manhattan -- Federal agents carried out a search warrant at the home and office of former New York City Mayor Rudy Giuliani Wednesday morning, sources familiar with the matter confirm to ABC News.
Sources tell ABC News, electronic devices, including Giuliani's cell phone, were confiscated by authorities.
The U.S. Attorney's Office has so far declined to comment.
Robert Costello issued a statement on Giuliani's behalf Wednesday night:
"The electronics taken are, also, replete with the material covered by the attorney-client privilege and other constitutional privileges. The warrant served on Mr. Giuliani's law office is another disturbing example of complete disregard for the attorney-client privilege protected by the Sixth Amendment to the Constitution."
Wednesday afternoon, Giuliani's son, Andrew, who is mulling run for New York governor, spoke briefly outside his father's apartment.
"Any American, red or blue, should be extremely disturbed by what happened here today," Andrew Giuliani said. "This is disgusting, this is absolutely absurd, and it's the continued politicization of the Justice Department that we have seen and it has to stop. If this can happen to the former president's lawyer, this can happen to any American."
The warrants were in relation to the Justice Department's investigation into the business dealings of former President Donald Trump's personal lawyer.
In the statement released by Costello, he says "The search warrants involve only one indication of an alleged incident of failure to register as a foreign agent. Mayor Giuliani has not only denied this allegation, but offered twice in the past two years through his attorney Bob Costello to demonstrate that it is entirely untrue."
The federal probe into Giuliani's Ukraine dealings stalled last year because of a dispute over investigative tactics as Trump unsuccessfully sought a second term. Giuliani subsequently took on a leading role in disputing the election results on the Republican's behalf.
Wednesday's raids came months after Trump left office and lost his ability to pardon allies for federal crimes. The former president himself no longer enjoys the legal protections the Oval Office once provided him - though there is no indication Trump is eyed in this probe.
Many people in Trump's orbit have previously been ensnared in federal investigations, namely special counsel Robert Mueller's probe of Russian election interference. But most of those criminal cases either fizzled or fell apart. Giuliani's is different.
Giuliani was central to the then-president's efforts to dig up dirt against Democratic rival Joe Biden and to press Ukraine for an investigation into Biden and his son, Hunter - who himself now faces a criminal tax probe by the Justice Department.
"The Biden department of justice has completely ignored clear evidence (which the FBI has had for over a year) in texts and emails on Hunter Biden's hard drive of failing to register numerous times as a foreign agent, child pornography, money laundering, and 30 years of the Biden Crime family taking millions and millions in bribes to sell his public offices," Costello said in reference to Hunter Biden.
Giuliani also sought to undermine former U.S. ambassador to Ukraine Marie Yovanovitch, who was pushed out on Trump's orders, and met several times with a Ukrainian lawmaker who released edited recordings of Biden in an effort to smear him before the election.
The federal Foreign Agents Registration Act requires people who lobby on behalf of a foreign government or entity to register with the Justice Department. The once-obscure law, aimed at improving transparency, has received a burst of attention in recent years - particularly during Mueller's probe, which revealed an array of foreign influence operations in the U.S.
Federal prosecutors in Manhattan had pushed last year for a search warrant for records, including some of Giuliani's communications, but officials in the Trump-era Justice Department would not sign off on the request, according to multiple people who insisted on anonymity to speak about the ongoing investigation with which they were familiar.
Officials in the then-deputy attorney general's office raised concerns about both the scope of the request, which they thought would contain communications that could be covered by legal privilege between Giuliani and Trump, and the method of obtaining the records, three of the people said.
The issue was widely expected to be revisited by the Justice Department once Attorney General Merrick Garland assumed office. Garland was confirmed last month and Deputy Attorney General Lisa Monaco was confirmed to her position and sworn in last week. The Justice Department requires that applications for search warrants served on lawyers be approved by senior department officials.
Information from the Associated Press was used in this report.