(WASHINGTON) — The Department of Justice has sent letters to six former Trump DOJ officials telling them that they can participate in Congress’ investigation into the Jan. 6 attack on the U.S. Capitol, according to sources and communications reviewed by ABC News.

The move is likely to remove a significant barrier that Democrats faced during Trump’s presidency, when the Justice Department backed the White House’s efforts to prevent any DOJ officials from testifying before their Democratic congressional committees.

At this time, no Trump-era DOJ official has indicated that they have agreed to testify in the congressional probe.

The first hearing of the House Select Committee to Investigate the January 6th Attack on the U.S. Capitol, featuring law enforcement officers who defended the Capitol on Jan. 6, got underway Tuesday.

Earlier, those attorneys who had been asked to testify had said they would need authorization from the Justice Department, sources told ABC News.

“Department attorneys, including those who have left the Department, are obligated to protect non-public information they learned in the course of their work,” reads the DOJ’s letter, which was sent Monday and reviewed by ABC News. “For decades and across administrations, however, the Department has sought to balance the Executive Branch’s confidentiality interests with Congress’s legitimate need to gather information. The extraordinary events in this matter constitute exceptional circumstances warranting an accommodation to Congress in this case.”

The letter was sent to former Acting Attorney General Jeffrey Rosen, former Principal Associate Deputy Attorney General Richard Donoghue, former Assistant Attorney General Jeffrey Clark, former U.S. Attorney for the Northern District of Georgia B.J. Pak, former U.S. Attorney for the Southern District of Georgia Bobby Christine and former Associate Deputy Attorney General Patrick Hovakimian, all of whom were requested as witnesses by House Oversight Committee.

“The extraordinary events in this matter constitute exceptional circumstances warranting an accommodation to Congress in this case,” the letter said. “Congress has articulated compelling legislative interests in the matters being investigated, and the information the Committees have requested from you bears directly on Congress’s interest in understanding these extraordinary events: namely, the question whether former President Trump sought to cause the Department to use its law enforcement and litigation authorities to advance his personal political interests with respect to the results of the 2020 presidential election.”

Copyright © 2021, ABC Audio. All rights reserved.