EXCLUSIVE: A top State Department official has accused Steve Linick, the department’s fired inspector general, of contacting a former colleague, obtaining official documents and returning to his former office -- all in violation of the terms of his administrative leave, Fox News has learned.

In a letter to Linick's attorney, obtained by Fox News, the State Department Under Secretary for Management Brian Bulatao says “in the days before his Congressional testimony, he sent a text message to the Deputy Inspector General, Diana Shaw, requesting a copy of the DOD IG report on the origins of a leak of a draft State OIG report to the media last fall. Without informing her own chain of command, we understand that Ms. Shaw then contacted the DOD Office of Inspector General to request a copy of the report on Mr. Linick’s behalf.”

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Bulatao also wrote that “it is not clear what Mr. Linick’s motivation was, but it was inappropriate for him to seek the DOD IG report through the State OIG, given that he was, at the time, on administrative leave pursuant to a decision by the President with a new Acting Inspector General in place."

The official added: "His apparent urgency is all the more unusual given that Mr. Linick had repeatedly refused to share the DOD IG report with anyone in the State Department itself.”

Bulatao also claims Linick “repeatedly returned to his former office without seeking authorization from his Department reporting chain, also contrary to the clear instructions he received.”

An attorney for Linick did not immediately return a request for comment from Fox News.

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President Trump fired Linick May 15 at the request of Secretary of State Mike Pompeo, igniting controversy.

Linick, at the time of his firing, had been investigating the State Department’s $7 billion arms sale to Saudi Arabia, despite congressional objections. Linick also was probing whether Pompeo misused department funds for personal errands such as walking his dog, making dinner reservations and picking up his dry cleaning.

Last week, Linick sat for a congressional interview where Democrats say he told them Bulatao tried to “bully” him as he investigated the State Department.

Linick also defended his work as “impartial” and “without regard to politics” during closed-door testimony on Capitol Hill.

He maintained that “every minute” of his work as inspector general “has been devoted to promoting the efficiency and effectiveness” of the agency and ensuring that taxpayer funds are protected against waste, fraud and abuse.

A handful of Senate Republicans have criticized the administration for failing to provide a reason for firing Linick.

Last week, Sen. Chuck Grassley, according to his office, announced he “is refusing to advance certain nominees until the White House provides adequate reasons for the termination of the Intelligence Community and State Department inspectors general."

Fox News' Brooke Singman contributed to this report.