The directors of the FBI and NSA are giving evidence before the House Intelligence Committee
The FBI has confirmed it is investigating any possible links between members of the Trump campaign and the Russian government.
Speaking at a US committee this afternoon, FBI director James Comey confirmed his organisation is "investigating the Russian government's efforts to interfere in 2016 presidential election".
"That includes investigating the nature of any links between individuals associated with the Trump campaign and the Russian government; and whether there was any co-ordination between the campaign and Russia's efforts," he said.
Mr Comey added: "As with any counter-intelligence investigation, this will also include an assessment of whether any crimes were committed."
He stressed he was unable to provide many details of the ongoing investigation in public, including 'whose conduct' is being investigated.
Mr Comey was giving evidence during the first public hearing into claims Russia meddled in the US election.
The House Intelligence Committee is looking into allegations of Russian hacking and any possible ties the Trump campaign may have had with Moscow.
Until now, investigations have been taking place behind closed doors.
The NSA's Mike Rogers is also appearing before the committee today.
The committee has also been examining Donald Trump's as yet unsubstantiated allegation that Barack Obama ordered a 'wiretap' of Trump Tower in New York.
Over the weekend, the committee confirmed that it has received no evidence to support President Trump's wiretapping allegations.
Chairman Devin Nunes told Fox News Sunday: “Was there a physical wiretap of Trump Tower? No... there never was, and the information we got on Friday continues to lead us in that direction."
Both Republican and Democratic politicians dismissed the claims at today's hearing, with Democrat Adam Schiff saying there was “no evidence whatsoever to support that slanderous accusation".
Claims of Russian interference in last year's presidential election have proven a headache for President Trump and his advisers over recent months.
National security adviser Michael Flynn resigned last month amid reports that he misled the administration over his talks with Russia.
Ahead of today's hearings, President Trump again dismissed any suggestion of collusion with Russia:
The Democrats made up and pushed the Russian story as an excuse for running a terrible campaign. Big advantage in Electoral College & lost!— Donald J. Trump (@realDonaldTrump) March 20, 2017
The real story that Congress, the FBI and all others should be looking into is the leaking of Classified information. Must find leaker now!— Donald J. Trump (@realDonaldTrump) March 20, 2017