Former Trump administration officials can testify to Congress about Donald Trump’s role in the deadly January attack on the Capitol and his efforts to subvert the results of the 2020 election, the justice department (DoJ) has said in a letter obtained by the Guardian.

The move by the justice department declined to assert executive privilege for Trump’s acting attorney general, Jeffrey Rosen, clearing the path for other top former officials to also testify to congressional committees investigating the Capitol attack without fear of repercussions.

The justice department authorised witnesses to appear specifically before the two committees. But a DoJ official, speaking on the condition of anonymity to discuss sensitive matters, said they expected that approval to extend to the 6 January select committee that began proceedings on Tuesday.

Bennie Thompson, the chairman of the House select committee, told the Guardian in a recent interview that he would investigate both Trump and anyone who communicated with the former president on 6 January, raising the prospect of depositions with an array of Trump officials.

Rosen and Trump administration witnesses can give “unrestricted testimony” to the Senate judiciary and House oversight committees, which are scrutinising the attempt by the Trump White House to stop Congress certifying Joe Biden’s 2020 election win, the letter said.

The justice department’s decision marks a sharp departure from the Trump era, when the department repeatedly intervened on behalf of top White House officials to assert executive privilege and shield them from congressional investigations into the former president.

It also represents a significant move by the White House Office of Legal Counsel under Biden, which in authorising the decision, pointedly noted that executive privilege protections exist to benefit the country, rather than a single individual.

Trump has argued that conversations and deliberations involving the president are always protected by executive privilege. He can sue to block any testimony, which would force the courts to decide the extent of such protections.

But the justice department said in the letter that Rosen and Trump administration officials can testify to Congress about Trump’s attempts to subvert the 2020 election because of the extraordinary nature of the circumstances.

In his last weeks in office, Trump pressured justice department officials to use the vast powers of the federal government to undo his defeat, asking them to investigate baseless conspiracies of voter fraud and tampering that they had already determined to be false.

“The extraordinary events in this matter constitute exceptional circumstances warranting an accommodation to Congress,” Bradley Weinsheimer, a senior career official in the office of the deputy attorney general, said in the letter.

The justice department told Rosen and Trump administration officials that they could appear before Congress as long as their testimony was confined to the scope set forth by the committees and did not reveal grand jury or classified information, or pending criminal cases.

Rosen’s approval letter, which was sent on Monday night according to a source familiar with the matter, comes after the Senate judiciary committee asked to interview several Trump administration officials as part of their oversight efforts started in January.

Negotiations for their testimony were stalled as the justice department weighed how much information former officials could reveal, concerned that many of the conversations were covered by executive privilege, which keeps executive branch deliberations confidential.

The justice department ultimately relented after consulting with the White House Office of Legal Counsel, which said it would not be appropriate to assert executive privilege over the specific topics in question, according to the letter.

“It is the executive branch’s view that this presents an exceptional situation in which the congressional need for information outweighs the Executive Branch’s interest in maintaining confidentiality,” wrote Weinsheimer, citing Richard Nixon and Watergate.

The Senate judiciary committee chairman, Dick Durbin, said on Twitter that he was working to now schedule interviews with the officials. The panel is also still receiving materials and documents from the justice department, the source said.

The House oversight committee chairwoman, Carolyn Maloney, said in a statement that she was pleased with the decision: “I am committed to getting to the bottom of the previous administration’s attempts to subvert the justice department and reverse a free and fair election.”

Trump exerted significant pressure on the justice department to help him remain president. In one instance, Trump schemed with Jeffrey Clark, the former head of the DoJ’s civil division, to force Georgia to overturn their election results, the New York Times reported.

The Senate judiciary and House oversight committees opened wide-ranging investigations into Trump and the justice department shortly after, with Durbin also demanding materials from the National Archives for records and communications concerning those efforts.