Lawyers for President Donald Trump tried to prevent former acting Attorney General Sally Yates from testifying before the House Intelligence Committee on links between Trump campaign staff and Russian officials, according to correspondence first obtained by The Washington Post.

In a series of letters last week, Yates’ lawyer, David O’Neil, accused the Trump Justice Department of trying to silence Yates by asserting that “all information Ms. Yates received or actions she took in her capacity as Deputy Attorney General and acting Attorney General are client confidences that she may not disclose absent written consent of the department.”

Yates served as deputy attorney general in the Obama administration and then as acting attorney general in the first few weeks of the Trump administration. Trump fired her on Jan. 31, after she refused to enforce the president’s original executive order banning immigrants from seven majority-Muslim countries.

O’Neil went on to write that he and his client disagreed with the idea that her testimony required permission. “We believe that the department’s position in this regard is overbroad, incorrect, and inconsistent with the department’s historical approach to the congressional testimony of current and former officials,’’ he wrote.

“In particular, we believe that Ms. Yates should not be obligated to refuse to provide non-classified facts about the department’s notification to the White House of concerns about the conduct of a senior official,” he wrote. “Requiring Ms. Yates to refuse to provide such information is particularly untenable given that multiple senior administration officials have publicly described the same events.’’

O’Neil emphasized that Yates would not reveal any classified information in the Intelligence Committee hearing.

On Friday, the Justice Department wrote back to say that any approval concerning testimony about communications with the White House needed to come not from the department but straight from the White House. O’Neil then wrote to White House Counsel Don McGahn, told him what the Justice Department had said, and informed him that Yates planned to testify Tuesday, March 28, as originally scheduled.

Within hours after that letter was sent on Friday, Intelligence Committee Chairman Devin Nunes (R-Calif.) canceled the scheduled hearing, which also would have included testimony from top intelligence officials. On Tuesday, the White House denied that it had taken any action to prevent Yates from testifying.

“The Washington Post story is entirely false,” said White House press secretary Sean Spicer in a statement. “The White House has taken no action to prevent Sally Yates from testifying and the Department of Justice specifically told her that it would not stop her and to suggest otherwise is completely irresponsible.”

“I hope she testifies. I look forward to it,” Spicer said at a press briefing on Tuesday afternoon. “We have no problem with her testifying, plain and simple.”

He also said that the House Intelligence Committee hearing in question was “never notified,” implying that the White House was unaware of it. In fact, the hearing had been posted on the committee’s public schedule for more than a week before it was postponed.

The canceled hearing is just the latest incident to raise questions about Nunes’ handling of the Trump-Russia investigation. The chairman also abruptly scrapped all of the committee’s meetings for the entire week, committee members said Tuesday morning.

Top Democrats, including members of his committee, have asked whether Nunes, who served on the Trump transition team, can conduct an independent and transparent investigation. They’re calling on Nunes to recuse himself from this investigation or for House Speaker Paul Ryan (R-Wis.) to remove him entirely as chair.

Nunes claimed last week that members of Trump’s transition team were subject to “incidental” surveillance. But one day before making that allegation, he met with a source on White House grounds, raising more questions about his transparency and credibility.

After holding a press conference about his surveillance claims, Nunes briefed Trump, whose team is also under FBI investigation for alleged ties to Russian officials who may have interfered in the 2016 U.S. election.

Nunes reiterated Tuesday morning that he does not intend to step down.

“Why would I?” he asked reporters on Capitol Hill.

At a press conference Tuesday, Ryan similarly said that he doesn’t think Nunes needs to recuse himself from the investigation.

The story has been updated with further comment from Sean Spicer.