The FBI has confirmed its investigating alleged Russian government efforts to interfere in last year's US election.
Investigators have also found there was no "wiretap on Trump Tower" - although they haven't ruled out the possibility that other surveillance techniques were used.
The hearing's also heard there's no evidence people's actual votes were tampered with.
Its director James Comey's been giving evidence to politicians about its inquiries:
Donald Trump has taken to Twitter to criticise the investigation, calling it "fake news" and accused the Democrats of making up the story as "an excuse for running a terrible campaign":
James Clapper and others stated that there is no evidence Potus colluded with Russia. This story is FAKE NEWS and everyone knows it!
— Donald J. Trump (@realDonaldTrump) March 20, 2017
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
