Moscow (AFP) - Russia's foreign minister on Tuesday said there was no evidence the country had interfered in US elections, after a Washington probe accelerated with charges against three former aides to Donald Trump's presidential campaign.

"We are accused of interfering not only in US elections but also in those of other countries without one piece of evidence," Sergei Lavrov told reporters in Moscow.

Russia has repeatedly denied any attempt to influence the 2016 presidential election.

On Monday Trump's ex-campaign chairman Paul Manafort and another former aide appeared in court, pleading not guilty to conspiracy against the US, money laundering and several other charges after the indictments in the Russia probe were unsealed.

Facebook, Google and Twitter are expected to tell Congress this week that Russian-backed content aimed at manipulating US politics during last year's election was more extensive than first thought, US media reported.

At a meeting of the Association of European Businesses, Lavrov also said that the "sometimes unpredictable" actions of the current US administration had caused "serious fears".

He pointed to threats to solve problems over the Korean peninsula by force, as well as Trump's refusal to certify the Iran nuclear deal.