Roger Stone - a longtime adviser to President Donald Trump - has been arrested in Florida and charged on seven counts.

That's according to a grand jury indictment, made public on Friday by Special Counsel Robert Mueller's office -- which is investigating possible collusion between Russia and Trump's 2016 election campaign.

Stone faces one count of obstruction of an official proceeding, five counts of making false statements and one count of witness tampering.

During Trump's 2016 election campaign, Stone posted messages on Twitter implying that he had inside knowledge of data in the possession of an organization that would embarrass the Democrats.

While the organization is unnamed in court documents, it matches the description of Wikileaks-- which in the months leading upto the election released emails hacked from computers used by Clinton's senior campaign adviser John Podesta and the Democratic National Committee.

Wikileaks has denied it obtained the material it released from the Russian government.

Stone denies having such inside or advance information - and denies any wrongdoing.

But according to the indictment Stone still possessed many of those communications when he gave false testimony about them.

A spokesman for the special counsel's office said Stone will appear in a Fort Lauderdale court later on Friday.