President Donald Trump is the subject of a whistleblower complaint of "urgent concern" that was filed in the intelligence community in August, The Washington Post reported Wednesday night.

The whistleblower lodged the complaint because the person was deeply troubled by a phone call Trump had with a foreign leader and, in particular, a "promise" Trump made during the call.

The House Intelligence Committee has demanded a full, unredacted copy of the complaint, but the Office of the Director of National Intelligence is refusing to turn it over.

The acting director of national intelligence is expected to testify publicly before the committee on September 26, with the intelligence community inspector general expected to testify in a closed session Thursday, according to Rep. Adam Schiff of the House Intelligence Committee.

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President Donald Trump is the subject of a whistleblower complaint of "urgent concern" that was filed with the intelligence community inspector general in August, The Washington Post reported on Wednesday.

Specifically, someone within the intelligence community was concerned by a phone call Trump had with a foreign leader, which was said to include a "promise" that was so deeply troubling to that official that the person decided to lodge a formal whistleblower complaint with the inspector general.

It's not clear who the leader was or what the substance of Trump's promise was, but the revelation raises new questions about the president's handling of classified information. It could also put more strain on Trump's already-tense relationship with the US intelligence community.

The Post reported that Trump interacted with at least five foreign leaders in the five weeks before the whistleblower filed the complaint: Russian President Vladimir Putin, North Korean leader Kim Jong Un, Pakistani Prime Minister Imran Khan, Dutch Prime Minister Mark Rutte, and Qatari Emir Sheikh Tamim bin Hamad Al Thani.

Putin is the only one Trump is known to have spoken on the phone with, a call Trump initiated.

The House Intelligence Committee is fighting with the Trump administration to obtain the full complaint

Democratic Rep. Adam Schiff, the chairman of the House Intelligence Committee, first revealed the existence of the complaint last week, when he subpoenaed the acting director of national intelligence, Joseph Maguire, to turn over the full complaint to the committee in accordance with federal law.

The intelligence community inspector general determined that the complaint was credible and a matter of "urgent concern." But the Office of the Director of National Intelligence overruled the inspector general after consulting with the Justice Department and concluding that the complaint did not fit the definition of "urgent concern" under federal law.

Trump in the Oval Office. Mark Wilson/Getty Images

Read more: The US's top spy agency just dropped a big hint that an 'urgent' whistleblower complaint involves Trump or someone close to him

The definition concerns serious allegations related to "the funding, administration or operation of an intelligence activity within the responsibility and authority" of the director of national intelligence, the Office of the Director of National Intelligence's general counsel, Jason Klitenic, wrote in the letter.

"This complaint, however, concerned conduct by someone outside the Intelligence Community and did not relate to any 'intelligence activity' under the DNI's supervision," Klitenic added. For that reason, after consulting with the Justice Department, the agency concluded it was not required to forward the complaint to the intelligence committees.

Schiff said on Tuesday that Klitenic's letter added to concerns that the Office of the Director of National Intelligence was acting to shield Trump or someone in his inner circle from public scrutiny.

In addition to flagging the complaint with the Justice Department — which itself is unusual for matters like these — Maguire also refused to comment on whether the White House was involved in the decision to withhold the complaint from the House Intelligence Committee and whether it related to any matters being investigated by the panel.

Schiff said on CBS News' "Face the Nation" on Sunday that Maguire said he was not turning over the complaint, even though federal law mandated it, "because he is being instructed not to" and "answering to a higher authority" on the matter.

"This involved a higher authority, someone above the DNI," Schiff said, alluding to Trump. "Well, there are only a few people above the DNI."

Schiff on Wednesday said that the intelligence community inspector general was expected to testify before the House Intelligence Committee in a closed session Thursday and that Maguire had agreed to testify publicly on September 26.