WASHINGTON — On the eve of his first news conference in more than five months, President-elect Donald Trump faces unverified allegations that Russian officials had gathered compromising information about his personal life and political associates, further deepening the controversy over Russian involvement in the 2016 election.

The information is contained in a 35-page file that was published Tuesday by BuzzFeed, which said it was publishing the material in the interest of “transparency” but had not been able to corroborate it.

Several news organizations reported that senior U.S. intelligence officials had included a two-page synopsis of the file in the materials they presented to Trump when they briefed him last week on evidence of Russian involvement in the election and that they had also informed top leaders of Congress about the allegations.

The purpose of including the material was to back up their conclusion that Russia had acted to hurt Hillary Clinton’s campaign, gathering information on both sides in the election but only publicly releasing information damaging the Democrats, according to CNN, which first reported on the briefing.

Trump responded in a tweet Tuesday evening that did not address any of the specific allegations, but denounced the stories.

The president-elect tweeted: “FAKE NEWS - A TOTAL POLITICAL WITCH HUNT!”

The material alleged that Russia for years had been “cultivating, supporting and assisting” Trump’s political rise and possessed damaging personal and financial information that could be used to blackmail him.

According to BuzzFeed and CNN, the dossier was compiled by a former British intelligence agent who was hired to do opposition research by Trump’s Republican opponents and later by Democrats. The report was prepared over the summer and was provided to U.S. analysts.

The two-page summary contained allegations that there was a “continuing exchange of information during the campaign between Trump surrogates and intermediaries for Russian government,” CNN reported, citing two national security officials.

It also alleged that information sharing between Trump’s team and the Russians went both ways. The Russians provided Trump’s aides with “valuable intelligence” on Clinton, the report said, while Trump’s associates gave Russian operatives information about Russian oligarchs.

CNN reported that the U.S. intelligence community vetted the former British operative and found him and his network of sources to be credible enough to justify including some of the information in reports provided to elected officials.

The existence of the file has circulated among political figures and reporters in Washington since at least October, when then-Sen. Harry Reid wrote a letter to FBI Director James Comey saying that the FBI possessed “explosive information about close ties and coordination between Donald Trump, his top advisers, and the Russian government.”

Mother Jones ran an article at that time reporting on the existence of the file and saying that the former British intelligence operative had provided his dossier to the FBI.

The report Tuesday became a viral sensation on social media, and even provided fodder for questioning at Sen. Jeff Sessions’ Senate confirmation hearing. Sessions, who was picked by Trump to be his attorney general, said he was not aware of the report and had no contacts with the Russian government.