FBI Director James Comey for the first time has publicly confirmed that his agency is investigating possible collusion between Russia and the Donald Trump campaign and whether any crimes were committed during the 2016 US elections.

"They wanted to hurt our democracy, hurt her (Democrat Hillary Clinton), help him (Trump). I think all three we were confident in at least as early as December (2016)," Comey said on Monday, CNN reported. 

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The Federal Bureau of Investigation is investigating whether there was any coordination between the Trump campaign and Moscow while Russia was interfering in the November 8, 2016 presidential election.

It is part of a wider probe into the hacking of Democratic servers and the Clinton campaign.

Comey also delivered an implicit rebuke to President Trump, saying that he had "no information" to support claims by the President that he was wiretapped on the orders of predecessor Barack Obama.

"I have no information that supports those tweets (by Trump)," Comey told the committee, adding that the Justice Department, along with the FBI, had no information to support the allegations.

Comey said that no President could order a wiretapping operation against a specific American citizen.

In a dramatic hearing before the House Intelligence Committee, Comey, once again finding himself at the epicentre of a political storm, also said that Russian President Vladimir Putin had a clear preference for whom he wanted to see as the next US President — and it was not Democratic nominee Hillary Clinton, CNN reported.

Comey's comments represented his most explicit intervention yet in the controversy over what US intelligence agencies have assessed was a Russian attempt to disrupt the election — and a string of counter-claims against the previous administration levelled by Trump himself.

"That includes investigating the nature of any links between individuals associated with the Trump campaign and the Russian government and whether there was any coordination between the campaign and Russia's efforts," Comey said in his opening statement to the committee.

The hearing, which also featured testimony from National Security Agency Director Mike Rogers saw Democrats highlight publicly available information about links between Trump associates and Russia. 

Republicans tried to turn the hearing into leaks that led to the resignation of former National Security Adviser Michael Flynn. 

Comey testified that US intelligence agencies were agreed that Russia's aim evolved into an effort during the election to aid Trump over Clinton.

The White House launched a political offensive even as the hearing was on.

Trump's spokesman Sean Spicer said Trump would not apologise to Obama for the accusations against him, adding that there were questions still remaining about surveillance that may or may not have taken place during the campaign, CNN reported.