The FBI has publicly challenged a push by Republican lawmakers to release a controversial memo which purports to show anti-Trump bias at the agency.
“We have grave concerns about the material omissions of fact that fundamentally impact the memo’s accuracy,” the FBI said in a statement.
The White House has reportedly indicated it could be published later on Thursday.
Democrats say the memo is an attempt to discredit the FBI-led Russia inquiry.
The White House has to approve the top-secret memo’s release.
“It will be released here pretty quick, I think, and the whole world can see it,” White House chief of staff John Kelly told Fox News Radio.
Hours later, the FBI issued a rare statement saying it had had “limited opportunity” to review the document before the House Intelligence committee voted to release it on Monday.
“We are committed to working with the appropriate oversight entities to ensure the continuing integrity of the Fisa [Foreign Intelligence Surveillance Act] process,” the FBI statement added.
On Wednesday night Democrats on the committee accused the Republicans of having secretly altered the memo before giving it to the White House.
Representative Adam Schiff said the document had “material changes”, meaning it was not the same as the one voted on. He said it should be withdrawn and reviewed again prior to any possible public release.
What is the memo?
The four-page document, compiled by staffers for House Intelligence Committee Chairman Devin Nunes, says the Department of Justice abused the Fisa surveillance programme to unfairly target a member of Donald Trump’s campaign.
According to lawmakers who have reviewed it, the document purports to show the agency obtained a warrant to spy on a Trump campaign aide after submitting as evidence the unproven “Russian dossier”.
That dossier was compiled by former UK intelligence agent Christopher Steele with money financed in part from the Hillary Clinton campaign.
The committee voted to release the memo earlier this week and Mr Trump has until the weekend to decide whether to de-classify the information for public release.
Mr Trump was heard following his State of the Union speech on Tuesday night telling a Republican lawmaker he was “100%” for releasing the document.
However, on Wednesday White House spokeswoman Sarah Sanders told CNN there was “always a chance” it would not be released.
Mr Kelly was less equivocal, saying Mr Trump wanted “everything out so the American people can make up their own minds and if there’s people to be held accountable, then so be it”.
Why is it controversial?
Before the FBI statement on Wednesday, the Department of Justice had already said it would be “extraordinary reckless” to release the document.
Democrats, whose efforts to release a competing memo were blocked by the committee, say Mr Nunes cherry-picked highly classified information which, they say, might jeopardise national security.
They argue the memo is an effort to embarrass the FBI and discredit the investigation, led by special counsel Robert Mueller, into alleged Russian meddling and possible obstruction of justice by members of the Trump administration.
But Trump officials say the memo proves his allegation that he has been treated unfairly by the FBI.
What is the latest reaction?
Chairman Nunes, who served on the Trump team during his White House transition, said it was “no surprise” the FBI has objected to the memo’s release.
“Having stonewalled Congress’ demands for information for nearly a year, it’s no surprise to see the FBI and DoJ issue spurious objections to allowing the American people to see information related to surveillance abuses at these agencies,” he said.
A top Democrat on the House committee, Adam Schiff, said releasing the memo increased “the risk of a constitutional crisis by setting the stage for subsequent actions by the White House to fire Mueller or, as now seems more likely, Deputy Attorney General Rod J Rosenstein”.
Democratic Senator Dianne Feinstein, who serves on the Senate Intelligence committee, said the Republicans were clearly trying to “undermine the special counsel’s investigation”.
“There’s no excuse for playing politics with highly classified information,” Mrs Feinstein added.