The US House Intelligence Committee, with the approval of US President Donald Trump, released a previously classified memo that raises concerns about FBI surveillance.
The release of the memo on Friday came amid protests from some elected officials and national law enforcement.
The memo, prepared by Republican legislator Devin Nunes, criticises suspected FBI surveillance abuses in relation to the investigation into Russian meddling in the 2016 presidential election.
"It's clear that top officials used unverified information in a court document to fuel a counter-intelligence investigation during an American political campaign," Nunes said in a statement.
The document says the FBI and Department of Justice obtained warrants to monitor Carter Page, a former foreign policy adviser to Trump during his 2016 presidential campaign, based on information from a disputed dossier on Trump compiled by a former British spy.
"I think it's a disgrace what's happening in our country. A lot of people should be ashamed of themselves and much worse than that," the president told reporters in the Oval Office on Friday.
The release of the memo comes as the president and Republicans intensified a conflict with the FBI.
Democrats have called the memo misleading and inaccurate.
Congressman Adam Schiff, the highest-ranking Democrat on the House Intelligence Committee, tweeted: "No, Mr President it's worse than that. The country's top elected leader has agreed to selectively and misleadingly release classified info to attack the FBI - that's what would have been unthinkable a short time ago."
Julian Sanchez, a senior fellow at the CATO Institute, told Al Jazeera that "part of the problem is that it's difficult to really assess what's said in the memo without a lot of contextual information."
He added: "What it seems to do is make a bunch of claims that seem to insinuate something bad was going on without actually saying it."
The feud between the FBI and the White House, an uncommon event in US politics, began last summer.
Trump fired then-FBI Director James Comey in May. The president cited concerns over the FBI's handling an investigation into the email servers of Hillary Clinton, Trump's opponent in the 2016 presidential election.
Detractors have said Trump's motivation for firing Comey involved the FBI's investigation into the affairs of the president and those close to him.
Robert Mueller, a former director of the FBI, was appointed as Special Counsel to head the Department of Justice investigation into Russian meddling in the 2016 election.
Reports surfaced last month that Trump considered firing Mueller, but reconsidered once senior members of his staff threatened to resign.