The White House has directed former counsel Donald McGahn not to comply with a congressional subpoena for documents related to special counsel Robert Mueller's investigation, current White House counsel Pat Cipollone said in a letter Tuesday.

McGahn was subpoenaed last month by House Judiciary Committee Chairman Jerrold Nadler, D-N.Y., for testimony and documents as part the panel's investigation into possible obstruction of justice by the president and others.

But in a letter to Nadler on Tuesday, Cipollone wrote that the subpoena seeks "certain White House records provided" to McGahn when he was White House counsel "with the clear understanding that the records remain subject to the control of the White House for all purposes."

Those documents "remain legally protected from disclosure under longstanding constitutional principles, because they implicate significant Executive Branch confidentiality interests and executive privilege," Cipollone said, adding that McGahn "does not have the legal right to disclose these documents."

Acting White House chief of staff Mick Mulvaney has directed McGahn not to produce the subpoenaed White House records, Cipollone continued, adding that the committee should direct any request for those records to the White House, which Cipollone said was the "appropriate legal custodian."

Cipollone wrote that the Department of Justice "is aware of and concurs with this legal position."

Cipollone's letter, however, does not mean the White House has asserted executive privilege. The letter indicates that while the White House considers the documents privileged, it hasn't invoked executive privilege to deny access to them.

Actual assertion of the privilege tends to be more formal, as laid out in a memo issued by President Ronald Reagan in 1982. It requires the president himself to make the final decision.

In a separate letter obtained by NBC News, William Burck, a lawyer for McGahn, told Nadler that the "co-equal branches of government" were "making contradictory demands" of his client and that McGahn would "maintain the status quo unless and until the Committee and the Executive Branch can reach an accommodation."

In a letter sent to Burck Tuesday, Nadler said that McGahn would face contempt proceedings if he did not appear.

"Mr. McGahn is required to appear and provide testimony before the Committee absent a court order authorizing non-compliance, as well as provide a privilege log for any documents withheld," Nadler wrote. "Otherwise, the Committee will have no choice but to resort to contempt proceedings to ensure that it has access to the information it requires to fulfill its constitutionally mandated duties."

McGahn had faced a Tuesday deadline to turn over several documents subpoenaed by House Democrats.

The development was first reported by ABC News.

In a statement, Rep. Doug Collins, R-Ga., the ranking member of the House Judiciary Committee, said that the White House was "seeking to accommodate Democrats' unwieldy demands."

While Mueller opted not to charge Trump with obstruction of justice, he laid out efforts by the president to tamper with witnesses and disrupt the investigation. The report said, for example, that Trump ordered McGahn to tell Deputy Attorney General Rod Rosenstein that "Mueller has to go."

Nadler said in a statement last month that Mueller's report indicates McGahn "is a critical witness to many of the alleged instances of obstruction of justice and other misconduct described in the Mueller report."

McGahn's testimony to Congress would help "shed further light on the President's attacks on the rule of law, and his attempts to cover up those actions by lying to the American people and requesting others do the same," Nadler said.

Mueller's nearly 450-page report detailed how McGahn had at least two phone calls with Trump in which the president "directed" him to contact Deputy Attorney General Rod Rosenstein to have Mueller "removed" — a key part of the special counsel's investigation into whether Trump obstructed justice.