US President Donald Trump says investigators have found no evidence of collusion with Russia, a day after prosecutors detailed a previously unknown attempt by a Russian to help his 2016 presidential election campaign.
"After two years and millions of pages of documents… no collusion!" Mr Trump tweeted on Saturday.
The alleged Russian approach was outlined in one of several court filings on Friday by US prosecutors and Special Counsel Robert Mueller seeking prison time for Mr Trump's former lawyer, Michael Cohen.
Cohen is to be sentenced next week for campaign finance violations, financial crimes and lying to Congress about Mr Trump's business dealings in Russia.
During discussions about a possible hotel bearing Mr Trump's name in Moscow, Cohen told prosecutors he was approached in November 2015 by an unnamed Russian claiming to be a "trusted person" in the Russian Federation, the filing said.
The Russian offered "synergy on a government level" with the Trump campaign in pushing for a meeting between Mr Trump and Russian President Vladimir Putin, it continued, adding that Cohen said he did not follow up.
Mr Mueller said that discussions about the potential Moscow development were relevant to his investigation because they occurred "at a time of sustained efforts by the Russian government to interfere with the US presidential election".
In a separate federal court filing on Friday, Mr Mueller's office said that Mr Trump's former campaign chairman, Paul Manafort, lied to investigators about his interactions with a Russian tied to Russian intelligence services.
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That filing detailed why Mr Mueller's office last week retracted a plea agreement with Manafort.
Manafort pleaded guilty in September to two conspiracy charges and agreed to co-operate with investigators in hopes of a lighter sentence.
Mr Mueller is investigating whether there was collusion between Mr Trump's 2016 presidential campaign and Russia, which US intelligence agencies say mounted an influence operation to sway the vote to Mr Trump over his Democratic rival, Hillary Clinton.
Russia denies interfering in the election to help Mr Trump.