US President-elect Donald Trump. REUTERS/Mike Segar Classified briefing materials provided to President Barack Obama and President-elect Donald Trump by US intelligence officials last week indicated that Russian operatives claimed to have compromising personal and financial information on Trump, according to CNN.

US intelligence officials gleaned the information from a former British intelligence operative who provided the FBI with a series of memos in August 2016 detailing how Russia has tried to cultivate Trump for at least five years.

The Kremlin denied these allegations in a statement Wednesday morning.

The British spy's findings — which were apparently based on conversations he had had with Russian intelligence sources — were summarized in a two-page synopsis that was appended to the US intelligence agency's report on Russia's interference in the 2016 election, CNN reported.

The material was not corroborated by intelligence agencies and could not be immediately verified independently. CNN said it was working to confirm the details contained in the memos composed by the unidentified British operative, who is apparently considered trustworthy by US intelligence officials.

Only Obama, Trump, and top lawmakers received the version of the report with a summary of the British operative's memos.

Trump responded to the reports in a tweet Tuesday evening.

"FAKE NEWS — A TOTAL POLITICAL WITCH HUNT!" he wrote.

The operative collected the information from Russian intelligence sources while he was doing opposition research for a project financed by anti-Trump Republicans. The information the operative collected indicated that Russia had compromising information on both Trump and Clinton but chose to release information that was potentially damaging only to the Clinton campaign.

BuzzFeed, which reported that the memos have been circulating around Washington for months, published the full dossier on Tuesday night, it said, "so that Americans can make up their own minds about allegations about the president-elect that have circulated at the highest levels of the US government."

Here are a few of the unverified details contained in the 35-page dossier that BuzzFeed published:

Russian officials allegedly fed Trump information about his political opponents including his Democratic presidential rival Hillary Clinton.

Russian officials reportedly offered Trump the opportunity to partner in real-estate development deals, which he did not participate in.

Trump hired sex workers, according to the report, to perform lewd acts referred to as "golden showers" in a Ritz Carlton presidential suite where President Obama once stayed.

"Trump's unorthodox behavior in Russia over the years," as the dossier described, provided Russians with information that they could potentially use to blackmail him.

Mother Jones cited the dossier in a report on the alleged Trump-Russia connection in October. The author of that story, David Corn, said he chose not to publish the full dossier because he could not confirm the allegations.

'A regular flow of intelligence from the Kremlin'

The memos authored by the operative claim that the Trump campaign and the Kremlin had established an "exchange of information" of "mutual benefit," and that Trump's lawyer, Michael Cohen, met secretly with Kremlin officials in Prague in August 2016.

Cohen denied the assertions contained in the memo.

"I have never been to Prague in my life. #fakenews," he tweeted, accompanied by a photo of his passport.

The memo also said that month earlier, Trump's adviser on foreign affairs, Carter Page, held secret meetings in Moscow with the president of Russia's state-owned oil company and a senior Kremlin internal affairs official, according to the dossier.

Carter Page, then adviser to Trump, speaking at the graduation ceremony for the New Economic School in Moscow on July 8. Associated Press/Pavel Golovkin

"So far Trump has declined various sweetener real estate business deals offered him in Russia ... but he and his inner circle have accepted a regular flow of intelligence from the Kremlin, including on his Democratic and other political rivals," the memo says.

The operative claimed that Russian intelligence sources said they had "compromised" Trump during his visits to Moscow and could "blackmail him" with evidence of his conduct, which included "perverted sexual acts arranged and monitored" by the Russian federal security service (FSB).

But the Russians, the operative says in the dossier, "promised not to use the 'kompromat' they hold on Trump as leverage, given high levels of voluntary cooperation forthcoming from his team."

The memo asserts that the Kremlin has "been cultivating, supporting and assisting TRUMP for at least 5 years. Aim, endorsed by PUTIN, has been to encourage splits and divisions in western alliance."

In October, former Senate Minority Leader Harry Reid wrote an open letter to FBI Director James Comey calling on him to release the "explosive information" he possesses about the "close ties and coordination between Donald Trump, his top advisors, and the Russian government — a foreign interest openly hostile to the United States."

Reid's former spokesman, Adam Jentleson, said Tuesday that Reid had seen the documents before writing the letter.

When asked about reports that Trump's campaign had contact with Russia during the election, Comey told the Senate Select Committee on Intelligence on Tuesday that he could "not comment in an open forum" on whether his agency was pursuing an investigation into the alleged ties.

Carl Bernstein, who contributed reporting to CNN's story on the British spy's revelations, tweeted in December that it was "essential for citizens/Congress to know holdings and debts and partners in Russia (especially) of Donald Trump and his companies."

Trump said frequently during the campaign that he supported mending ties with Russia. Recently, he said the US intelligence community should "move on" from its focus on the hacks targeting the Democratic National Committee and Hillary Clinton's presidential campaign chairman, John Podesta.

Chris Sanchez contributed to this report.