Former Pentagon chief Mark Esper, who was dismissed by Trump after the 2020 presidential election has sued the Pentagon.

Esper, who is set to release a memoir, had to submit the book to the Defence Department to be cross checked before publishing in order to release state secrets and now he has filed a lawsuit over redactions to the memoir.

In the lawsuit, Esper accuses the defence department of censoring portions of his manuscript “under the guise of classification”.

He was “disappointed” to have his right to free speech violated, he said.

Esper was appointed defence secretary in 2019 by former president Donald Trump, who fired him shortly after the November 2020 election.

His book, due to be released in May 2022, is an “unvarnished and candid memoir” of his time at the White House, according to the lawsuit filed in Washington, DC.

The lawsuit accuses the agency that he led for 18 months of “arbitrarily” editing out the text of A Sacred Oath that Mr Esper said was “crucial to telling important stories discussed in the manuscript”.

“No written explanation was offered to justify the deletions” and the Pentagon could not confirm that the redacted text contained classified information, the lawsuit said.

“I am more than disappointed the current administration is infringing on my First Amendment constitutional rights”.

Pentagon spokesman John Kirby responding to the lawsuit said:

“As with all such reviews, the department takes seriously its obligation to balance national security with an author’s narrative desire.”

On 9 November, 2020, shortly after losing the general election to Joe Biden, Trump wrote in a tweet that the Gulf War veteran had been “terminated” from the top Pentagon job.

According to a new book by an ABC correspondent, reasons for the sack included Esper’s decision to bar Confederate flags from military bases, his public opposition to Trump’s desire to use American military forces to put down racial justice riots, and Esper’s focus on threats from Russia.

The Trump administration also tried to stop the publication of a memoir written by John Bolton, the former president’s National Security Advisor, from being published but failed.