A top U.S. federal prosecutor whose office has been investigating Rudolph W. Giuliani, the personal lawyer of U.S. President Donald Trump, said on Friday evening he would not leave his position, hours after the Trump administration abruptly said it was replacing him.

"I learned in a press release from the Attorney General tonight that I was 'stepping down' as United States Attorney. I have not resigned, and have no intention of resigning my position, to which I was appointed by the Judges of the United States District Court for the Southern District of New York," Manhattan U.S. Attorney Geoffrey Berman said in a statement.

The unusual statement by the U.S. Attorney in Manhattan, Geoffrey Berman, sets up a dramatic confrontation within the Justice Department over the high-profile position in a year when Trump is seeking reelection.

Berman said that until a presidentially appointed nominee was confirmed by the Senate, the office's "investigations will move forward without delay or interruption."

The statement came just hours after Barr in a surprise move said in a press release that Trump intends to nominate Securities and Exchange Commission Chairman Jay Clayton to replace Berman.

The reason for Berman's departure could not be immediately determined.

Since being appointed to the post in January 2018, Berman has not shied from taking on powerful figures in Trump's orbit.

He oversaw the prosecution of Michael Cohen, Trump's former personal lawyer, indicted two Giuliani associates and launched a probe into Giuliani in connection with his efforts to dig up dirt in the Ukraine on Trump's political adversaries.

While the Senate considers Clayton's nomination, Trump has appointed Craig Carpenito, currently the U.S. attorney for the District of New Jersey, to serve as the acting U.S. attorney for the Southern District, Barr said in his statement.

Berman, who served on Trump's transition team, could not immediately be reached for comment. Berman had replaced Preet Bharara, who was himself fired soon after Trump became president.

Bharara said the timing and manner of the move to replace Berman was strange.

"Why does a president get rid of his own hand-picked US Attorney in SDNY on a Friday night, less than 5 months before the election?" Bharara wrote on Twitter.

Clayton, a former Wall Street lawyer seen as a bipartisan consensus-builder during his time leading the SEC, also could not immediately be reached for comment.

(With input from Reuters)