Washington — Justice Department officials have been "quietly" reviewing records and documents from Ukraine for "several weeks," a source familiar with the matter tells CBS News.

The source said staff outside of Main Justice in Washington have been assigned by Attorney General William Barr to review the Ukraine matter, adding that the review is being handled by the U.S. Attorney's Office in Pittsburgh and is separate from U.S. Attorney John Durham's probe into the origins of the FBI's Russia probe.

The new review includes some material provided by Rudy Giuliani, the president's personal attorney, but goes beyond matters regarding former Vice President Joe Biden and his son, Hunter, who served on the board of a Ukrainian energy company.

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President Trump urged the president of Ukraine to investigate the Bidens and supposed Ukrainian election interference in a July 2019 phone call that eventually led to his impeachment. Democrats charged him with abusing his power by pressuring a foreign leader to investigate his domestic political opponent.

But calls to investigate the Bidens and events in Ukraine have gained new life in the wake of Mr. Trump's acquittal in his Senate impeachment trial.

On Sunday, Senator Lindsey Graham, the chairman of the Senate Judiciary Committee, told "Face the Nation" that Barr had established a process for Giuliani to submit information that he collected in Ukraine to the Justice Department. Graham warned that any material coming from the former Soviet republic "could be Russian propaganda."

On Monday, Barr said the Justice Department had "an open door to anybody who wishes to provide us information that they think is relevant" and had established an "intake process in the field" for receiving and verifying material from Ukraine. He said any information from Giuliani or others would be "carefully scrutinized by the department and its intelligence community partners so that we could assess its provenance and its credibility."

"We have to be very careful with respect to any information coming from the Ukraine," Barr said at an unrelated press conference. "There are a lot of agendas in the Ukraine. There are a lot of crosscurrents. And we can't take anything we receive from the Ukraine at face value.'

Democrats reacted with fury over the Justice Department's willingness to examine material about Ukraine and the Bidens, accusing the administration of once again targeting the president's political rivals based on spurious allegations. House Judiciary Committee Chairman Jerry Nadler wrote a letter to Barr expressing his "serious concern" over the situation and demanding answers about the "intake process."

"As you know, the Department has formal, established channels by which to receive information and begin investigations," Nadler wrote. "This new channel to Mr. Giuliani would seem to be a significant departure from those traditional channels."