US President Donald Trump's longtime political ally Roger Stone pleaded not guilty on Tuesday to making false statements to Congress and other charges brought in the investigation into Russia's role in the 2016 presidential election.

Stone, a self-proclaimed "dirty trickster" and Republican political operative for decades, also pleaded not guilty in a federal court in Washington, DC, to obstructing an official proceeding and witness tampering.

He is the latest member of Trump's inner circle charged in Special Counsel Robert Mueller's Russia investigation and was arrested on Friday in an early-morning raid on his home in Florida.

Prosecutors say Stone told members of Trump's 2016 presidential campaign that he had advance knowledge of plans by the WikiLeaks website to release damaging emails about Trump's Democratic opponent, Hillary Clinton, that US intelligence agencies have concluded were stolen by Russia.

The indictment did not indicate whether Stone knew that Russians had stolen the emails by hacking into computers used by Clinton's senior campaign adviser John Podesta and the Democratic National Committee.

The 66-year-old could face about 50 years in prison if found guilty on all the charges but he is unlikely to receive such a harsh sentence, sentencing experts say.

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Stone, a Republican operative since the days of the Watergate scandal that forced his former boss, President Richard Nixon, to resign in 1974, smiled as he passed through a gauntlet of reporters upon arrival at the courthouse on Tuesday. A small group of protesters waved Russian flags and a placard that said "Dirty Traitor" while other people showed their support for him.

Stone had held an impromptu news conference after being released from custody after his arrest and gave interviews during the weekend but he did not speak to the media after the brief arraignment in Washington, DC.

Mueller 'close to wrapping up probe'

The charges against Stone marked the first time Mueller's team has publicly tied the Trump campaign to WikiLeaks and raise questions about what Trump may have known prior to the public release of the stolen emails.

Mueller last year charged 12 Russians accused in the hacking as part of his investigation of Russia's role in the election, whether Trump's campaign conspired with Moscow and whether the president has unlawfully sought to obstruct the investigation.

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The charging documents said a senior campaign official "was directed to contact Stone about any additional releases and what other damaging information" WikiLeaks had about Clinton's campaign but do not disclose the identity of the person who gave the order.

Stone, who is free on a $250,000 bond, has accused Mueller of "a raw abuse of power".

Trump has called the investigation a "witch-hunt" and denied any collusion. Russia has denied US intelligence community's finding that Moscow interfered in the US political arena.

Thirty-four people have been swept up in the Mueller investigation. Those charged include Trump's former campaign chairman and deputy campaign chairman, former national security adviser and his former personal lawyer.

It remains unclear whether any further charges have been filed. Acting US Attorney General Matthew Whitaker on Monday said Mueller's investigation was close to wrapping up and that a report was expected soon.