Intelligence chiefs have reportedly been unable to verify the claims contained in a dossier published online
Spy agencies should not have allowed a report which claims Russia has compromising intelligence on him to be leaked, Donald Trump has said.
The dossier reportedly alleges Russia obtained compromising material on the President-elect.
The unsubstantiated document - which it has been reported was compiled by a retired British spy - was dismissed by Mr Trump as "fake news" on Wednesday.
In a series of fresh tweets, the real estate mogul said: "Russia has never tried to use leverage over me. I HAVE NOTHING TO DO WITH RUSSIA - NO DEALS, NO LOANS, NO NOTHING!"
He went on:
I win an election easily, a great "movement" is verified, and crooked opponents try to belittle our victory with FAKE NEWS. A sorry state!— Donald J. Trump (@realDonaldTrump) January 11, 2017
Intelligence agencies should never have allowed this fake news to "leak" into the public. One last shot at me.Are we living in Nazi Germany?— Donald J. Trump (@realDonaldTrump) January 11, 2017
Intelligence chiefs have reportedly been unable to verify the claims, which Russia has dismissed as "utter nonsense".
"The Kremlin does not have compromising information on Trump," Russian President Vladimir Putin's spokesman Dmitry Peskov said.
He also denied Russia was in possession of damaging material on Mr Trump's defeated Democratic rival Hillary Clinton.
The dossier is also said to have included allegations of ongoing contact between associates of Mr Trump and intermediaries for the Kremlin.
Intelligence chiefs have reportedly been unable to verify the claims, but they were apparently considered sufficiently serious to be included in a highly-classified report on alleged Russian interference in the US presidential election.
The documents - apparently gleaned from sources in Russia and the US - claim the Russian regime has been "cultivating, supporting and assisting" Mr Trump for at least five years.
The material - reportedly compiled for Democratic and Republican opponents of the President-elect - has circulated for months in the US but has now been published in full by BuzzFeed.
However, BuzzFeed notes that the report contains "potentially unverifiable" claims, and flags several 'clear errors' contained in the document.
A spokesman for Harry Reid has said the former Senate Democratic leader saw the memos before writing a public letter to FBI Director James Comey about Trump's ties to Russia.
In the letter, he wrote: "It has become clear that you possess explosive information about close ties and coordination between Donald Trump, his top advisors, and the Russian government - a foreign interest openly hostile to the United States."
"A political witch hunt"
According to CNN, Senator John McCain - chair of the Senate Armed Services Committee, which is investigating alleged Russian hacking of the election - also gave a full copy of the memos to Mr Comey on 9 December.
As details of the report emerged the President-elect first tweeted:
FAKE NEWS - A TOTAL POLITICAL WITCH HUNT!— Donald J. Trump (@realDonaldTrump) January 11, 2017
He also retweeted a story suggesting the stories were 'unverifiable'.
Michael Cohen, a special counsel for Mr Trump, has denied a claim in the document that he met with Kremlin officials in Prague - claiming he has never even been to the city.
Victoria Jones, Chief White House Correspondent with Talk Radio News in the US, spoke to Newstalk Breakfast about the news.
She explained: "Most news outlets are thrashing BuzzFeed's decision to publish it, because it is unverified. Many news outlets and journalists had this information before the election, and really good journalists chose not to go with this because they were verifying it. Intelligence had this, and they were verifying it.
"Yes, there is credence possibly given to this, because the former British intelligence officer who is said to have put this together is considered credible, is considered to have very good relations with Russian intelligence. But [...] it was done as opposition research," she added.
The Guardian reports that the FBI applied for a warrant from the foreign intelligence surveillance (Fisa) court over the summer in order to monitor four members of the Trump team suspected of irregular contacts with Russian officials.
The court turned down the request, asking FBI counter-intelligence investigators to narrow its focus.
Mr Comey refused to say whether the FBI was investigating allegations of links between Trump associates and the Kremlin when questioned by the Senate Intelligence Committee on Tuesday.
Mr Trump has consistently defied the consensus of 17 US intelligence agencies - playing down claims that Russia interfered with the election to help him win.
Last month he said: "It's time for our country to move on to bigger and better things."