US president-elect Donald Trump promised today that his "people" will release a full report on hacking within 90 days.

The promise came amid a series of three tweets rebuffing recent allegations that Russian intelligence has a secret file of compromising information about the next president.

"Totally made up facts by sleazebag political operatives, both Democrats and Republicans - FAKE NEWS! Russia says nothing exists. Probably released by 'Intelligence' even knowing there is no proof, and never will be," Trump tweeted.

However, no hacking was alleged in that case. Rather, the information was allegedly leaked by a British spy who gained access to a larger report about allegations of Russian hacking attacks in 2015 and 2016 designed to affect the outcome of last year's presidential election.

The dossier of unverified information Russia has on Trump was an addendum to that report.

Given Trump's free flow of information on Twitter, it is impossible to say which issue would be the focus of his promised probe, or whether he would have both looked at.

"My people will have a full report on hacking within 90 days!" he wrote, without clarifying to whom he would give the job.

His tirade today also blasted his Democratic competitor in last year's election, Hillary Clinton, as "guilty as hell," amid reports the FBI is under scrutiny for the way it went about providing details into its investigation of her alleged mishandling of government email on a private server while secretary of state.

Trump additionally attributed her loss to campaigning "in the wrong states"; praised the anticipated repeal of President Barack Obama's signature healthcare law; and praised his cabinet picks for speaking their minds during ongoing confirmation hearings, even if they have contradicted him on critical issues in the last few days.

"All of my cabinet nominees are looking good and doing a great job. I want them to be themselves and express their own thoughts, not mine!"

In London today, a former British ambassador to Russia told the media he spoke to US Senator John McCain months ago about the "dirty dossier" on Trump and his alleged links to Russia.

'Dossier passed to FBI'

The senior Republican senator admitted that he passed to the FBI the dossier that contained unverified claims about compromising information the Russians may have on the president-elect.

Trump has denied the allegations and dismissed the dossier as "nonsense" and "fake news."

The document was allegedly compiled by a British ex-spy and it has been suggested McCain obtained it from a former British ambassador to Moscow.

Andrew Wood, who held the post from 1995 to 2000, denied having seen the dossier but told the Today programme on BBC Radio 4 that he discussed the rumours with McCain at a security conference in November.

"We spoke about the kind of activities the Russians can be engaged in," Wood said.

"We also spoke about how Mr Trump may find himself in a position where there could be an attempt to blackmail him with Kompromat (compromising material) and claims that there were audio and video tapes in existence."

Britain's new ambassador to the EU Tim Barrow has also denied any involvement in circulating the document.

- dpa