The FBI said Wednesday it has “grave concerns” about the veracity of a classified memo prepared by a lawmaker who backs President Trump that accuses the bureau and the Justice Department of improper surveillance of a Russia-linked ex-Trump adviser.

“As expressed during our initial review, we have grave concerns about the material omissions of fact that fundamentally impact the memo’s accuracy,’’ the FBI said in a statement.

The bureau also said it meticulously adheres to the stringent rules mandated by the Foreign Intelligence Surveillance Act, which provides a legal framework for investigations involving national security.

“The FBI takes seriously its obligations to the FISA Court and its compliance with procedures overseen by career professionals in the Department of Justice and the FBI. We are committed to working with the appropriate oversight entities to ensure the continuing integrity of the FISA process,’’ the statement said.

White House chief of staff John Kelly wants the memo prepared by Rep. Devin Nunes (R-California) released “pretty quick” — setting up a remarkable showdown between the White House and its own law top enforcement officials.

“It will be released here pretty quick, I think, and then the whole world can see it,” Kelly told Fox News Radio on Wednesday, adding that he has seen the Republican-written document and that White House and national security lawyers are currently reviewing it.

“This president … he wants everything out so the American people can make up their own minds and if people need to be held accountable, so be it,” he continued.

FBI Director Christopher Wray and Deputy Attorney General Rod Rosenstein on Monday made a last-minute plea to Kelly to tell the president that the four-page memo could damage national security and set a dangerous precedent for the handling of classified materials, according to the Washington Post.

Wray, who was allowed to view the memo Sunday, also told Kelly that the document contains inaccurate information and creates a false narrative, Bloomberg reported Wednesday.

The Washington Post story came out just before Trump was heard on an open mic after his State of the Union address Tuesday evening saying he’s “100 percent” behind making the memo public.

Kelly told Wray and Rosenstein that Trump was still inclined to publicly release the document, but would first have the National Security Council and the White House counsel review it, which could take several days.

Their appeal Monday came just before members of the GOP-controlled House Intelligence Committee voted along party lines to release it, giving Trump a five-day window to make a decision.

Nunes, the panel’s chairman and a member of the Trump transition team, and other Republicans wrote the memo that reportedly includes allegations that the DOJ and FBI used some of the information in a controversial dossier to seek a warrant to spy on former Trump campaign staffer Carter Page.

Democrats on the panel say Nunes cherry-picked information from classified material to construct an inaccurate narrative.

The dossier, compiled by former British super-spy Christopher Steele, connects Trump and Russian officials, though it has not publicly been verified.

It was bankrolled at first by a conservative media outlet targeting Trump, and later by Hillary Clinton’s presidential campaign and the Democratic National Committee after it became clear that Trump would win the nomination.