White House aides falsely claimed former national security adviser John Bolton's book contained classified information to prevent publication, a lawyer for a former career official overseeing the book’s prepublication review said in a letter filed in court on Wednesday.

Ellen Knight, the former official, said aides blocked a request from Bolton to review his account of President Donald Trump’s dealings with Ukraine, a section Bolton wanted to release during Trump's impeachment trial, attorney Kenneth Wainstein said in the letter obtained by The New York Times.

Wainstein said his client learned in April that Bolton’s book, “The Room Where It Happened,” did not contain any classified information.

The revelations contradict accusations by the president and other administration officials, alleging Bolton's book contains highly sensitive material.

The White House hired attorney Michael Ellis, a former aide to Rep. Devin Nunes, R-Calif., a close Trump ally, to conduct a separate review. Ellis has no prior experience reviewing manuscripts and went through the proper training after completing his review, the Times reported. Ellis’s findings said the book contained classified information, prompting the Justice Department to seek a court order to block distribution.

“Rather than evaluating the book by prepublication review standards for writings by a private citizen, he essentially treated the manuscript as a government document being subject to a classification review,” the letter said.

Wainstein added the review was “commandeered by political appointees for a seemingly political purpose.” Knight said the actions she was asked to take were “unprecedented in her experience.”

“She had never previously been asked to take the above-described measures, and she has never heard that predecessors in her position ever received such instructions in the course of their prepublication reviews,” the letter said.