Russian President Vladimir Putin ordered an "influence campaign" aimed at hurting Hillary Clinton and helping Donald Trump win in the 2016 presidential election, the US intelligence has revealed in a unclassified report.

The 25-page report released on Friday was the first official, full and public accounting by the US intelligence community of its assessment of Russian cyberhacking activities during the 2016 campaign and the motivations behind that hacking, CNN reported.

"We assess Russian President Vladimir Putin ordered an influence campaign in 2016 aimed at the US presidential election," the report said. 

"Russia's goals were to undermine public faith in the US democratic process, denigrate Secretary Clinton, and harm her electability and potential presidency. We further assess Putin and the Russian Government developed a clear preference for President-elect Trump."

"Russian efforts to influence the 2016 US presidential election ' title=' US presidential election '>US presidential election represent the most recent expression of Moscow's longstanding desire to undermine the US-led liberal democratic order, but these activities demonstrated a significant escalation in directness, level of activity, and scope of effort compared to previous operations," it continued.

The report said Moscow used a variety of tactics in a bid to sway the outcome.

"Moscow's influence campaign followed a Russian messaging strategy that blends covert intelligence operations -- such as cyberactivity -- with overt efforts by Russian government agencies, state-funded media, third-party intermediaries and paid social media users or 'trolls', " the report found.

The US intelligence community also released several new pieces of information to support its conclusions, CNN noted.

It noted that in the final run-up to the election, when majority of the polls favoured Clinton to win the election, Moscow shifted its campaign to influence the election to one aimed at undermining the validity of the electoral results.

"Before the election, Russian diplomats had already publicly denounced the US electoral process and were prepared to publicly call into question the validity of the results," the report stated, adding that pro-Russian government bloggers had prepared a Twitter campaign on Election Night using the hashtag "#DemocracyRIP".

President-elect Donald Trump was briefed earlier on Friday on the report by top US intelligence and law enforcement officials, and while he said he had "a constructive meeting", he declined to publicly agree with their conclusions.

Instead, Trump stressed that "there was absolutely no effect on the outcome whatsoever".

Trump did acknowledge in his statement the possibility that Russia could have been behind the hack, though he named China as well as a persistent cyberhacker.

However, there was no immediate response from Russian officials, although they have denied all the hacking claims, CNN said.

The US intelligence community also warned in its report that Moscow would likely continue to pursue cyberhacking campaigns to influence future elections.

"Moscow will apply lessons learned from its Putin-ordered campaign aimed at the US presidential election ' title=' US presidential election '>US presidential election to future influence efforts worldwide, including against US allies and their election processes," it added.

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