Former US Secretary of Defense Mark Esper has sued the Defence Department accusing Pentagon officials of blocking parts of his memoir.

“Significant text is being improperly withheld from publication in Secretary Esper’s manuscript under the guise of classification,” Mr Esper’s lawsuit filed in Federal District Court in Washington, DC, says, as quoted by The New York Times on Sunday.

According to the suit, the withheld text is “crucial” to telling certain important stories about his tenure under former US President Donald Trump.

“I am more than disappointed the current administration is infringing on my First Amendment constitutional rights. And it is with regret that legal recourse is the only path now available for me to tell my full story to the American people,” Mr Esper said in a statement on Sunday.

According to The New York Times, the Pentagon is aware of the former defence secretary’s concerns.

Mr Esper’s book, titled “A Sacred Oath” is due to be published in May 2022. Mr Esper submitted the manuscript to the Pentagon for review in May 2021 and received a list of requested redactions earlier this fall.

Former US President Donald Trump fired Mr Esper from the defence chief post last November. Mr Esper had been expected to be let go since at least June 2020, after disagreeing with Mr Trump on various issues such as opposing the US president’s idea of using active-duty troops to quell unrest and riots in the wake of George Floyd’s death in police custody.