Donald Trump has promised to issue a report within 90 days on allegations of Russian hacking during the US presidential election campaign.
In a series of tweets, the president-elect called the claims “made-up facts by sleazebag political operatives”.
US intelligence agencies have accused Russia of interfering in the election by hacking party communications.
They are also weighing claims that Moscow is holding compromising information about Mr Trump.
On Thursday the president-elect said Director of National Intelligence James Clapper had called him to “denounce the false and fictitious” reports of a Russian dossier against him, which were leaked to media earlier in the week.
But Mr Clapper said he had told Mr Trump that no judgement had so far been made on the reliability of the reports.
He also denied that intelligence agencies had originated the leaks.
The reports have deepened a rift between Mr Trump and the US intelligence community.
In his first news conference as president-elect on Wednesday, Mr Trump said it would be a “tremendous blot” on the reputation of US intelligence agencies if they had leaked information.
“That’s something that Nazi Germany would have done,” he said.
What is the Russian dossier?
On Tuesday, the Buzzfeed website published a 35-page document – which had been circulating in political and media circles before the election – claiming that Russia has damaging information about the president-elect’s business interests, and footage of him using prostitutes during a visit to Moscow.
Russia dismissed the allegations as “pulp fiction”.
The dossier, which is believed to have been commissioned initially by Republicans opposed to Mr Trump, was prepared by a former MI6 officer who now runs a London-based private consultancy.
Christopher Steele, who was formerly based in Moscow with the British foreign spy agency, is believed to have left his home this week and is now in hiding, the BBC understands.
Alleged Russian interference in election
Earlier this month intelligence agencies release the unclassified version of a report alleging that the Russian government had a “clear preference” for Mr Trump to win US election.
It said President Vladimir Putin had ordered a campaign to “undermine public faith in US democratic process” and “denigrate” Democratic candidate Hillary Clinton.
It also said Russian military intelligence had hacked into the email accounts of the Democratic National Committee and top Democrats, and used intermediaries such as WikiLeaks to release the information.
It claimed that Russia had also collected data from Republican-affiliated targets but had not conducted a comparable disclosure campaign.
Mr Trump’s spokesman has said the president-elect accepts the intelligence report, but added that there is no evidence that the outcome of the election was affected.