Donald Trump has praised one of his most controversial ex-advisers in a new documentary - even though it makes him out to be the real mastermind behind the President, and he faces an FBI probe.

In 'Get Me Roger Stone' Trump says that Roger Stone is a 'quality guy' and that he does not deserve his reputation as a dirty trickster.

Trump says that he has been friends with Stone for a long time and thinks he is a 'really nice' person who understands politics like few others do.

The President's comments in an interview for the documentary, which is out next month on Netflix, may prove to be awkward, given that the central argument of the film is that Stone is responsible for Trump getting into the White House.

Trump is also standing by Stone despite him being investigated by the FBI and the Senate over his ties to Russia.

In the film Stone says that Julian Assange, the founder of Wikileaks, is a 'hero', even though intelligence agencies believe that the Russians provided the website with hacked emails from the Democrats.

Stone is a provocateur and colorful character who has been a high level Republican operative for decades and worked for Presidents Nixon, Reagan and George H W Bush.

Stone, 64, a self styled dandy whose normal taste is for pinstripe suits, is also known for his win at all costs approach to politics his critics see as at best amoral.

Trump's interview for 'Get Me Roger Stone' took place in Trump Tower before he was elected to the Presidency.

Trump says: 'Roger has a really rough reputation.

'They talk about dirty trickster and lots of other things but I've known him for a long time and he's actually a quality guy, a really nice guy.

'Roger has a great understanding of the media. He understands politics and her understands politicians and he always likes to take on somebody who has a good chance of winning.

'Sometimes it doesn't work out, he's had some people that I said what are you doing. But he loves it, he loves the game and he has fun with it and he's very good at it'.

Trump says that Stone was the driving force behind his aborted run for the presidency in 1988 and then considering running to be the Reform party candidate in 2000.

He says: 'Roger always wanted me to run for president and over the years every time a presidential race came up he wanted me to run and I just didn't have interest at that time.'

Despite the praise, 'Get Me Roger Stone' makes it look like Stone is in charge of the President, an idea which will likely enrage Trump who recently sidelined his chief strategist Steve Bannon for reportedly taking too much of the credit for his boss' accomplishments.

Trump is said to have become angry when Bannon appeared on the front cover of Newsweek with the headline: 'The Great Manipulator'.

In the film Stone says that one of his rules is that the 'past is prologue' and that slogans like the silent majority, forgotten Americans and being the candidate of law and order are things he passed on to Trump having seen them work under previous Republican presidents.

Stone says that he looked at these ideas and 'just saw Trump's ability to use it to become President'.

He calls the Trump presidency a 'manifestation of a dream I've had since 1988' and says that he is a 'prime piece of political horseflesh'.

Stone says: 'I've always thought that Donald Trump had the size and the courage and the balls to become President of the United States'.

He also praises Bannon and says that he is a 'bomb thrower in the Stone mould' and Trump's 'secret weapon'.

'Bomb thrower': Stone praises Steve Bannon's the president's most controversial official White House aide

Paul Manafort, Trump's former campaign manager who was forced to resign amid controversy over his own dealings with Russia, says that in 1988 Stone 'saw the value of the outsider image' that Trump embodied and wanted him to run for the Presidency.

Manafort says that Stone 'saw something that nobody else saw' - and worked on it for the next three decades.

According to Manafort, even though Stone was forced to formally leave the Trump campaign as an adviser last summer, he 'continued to be a very important adviser and is to this day'.

Speaking before the election Manafort says: 'Roger's relationship with Trump is so interconnected it's hard to define what's Roger and what's Donald. While it will clearly be a Trump Presidency, I think it's influenced by Stone's philosophy.

'Roger's relationship with Trump, they both see the world from very similar ways. If Trump is elected Pres Roger will see one more very significant impact he's had on world history'.

'Get Me Roger Stone' will have its world premiere next week at the Tribeca Film Festival.

The film was directed by Daniel DiMauro, Dylan Bank and Morgan Pehme, three New York-based filmmakers who followed him around for five years. It will be released on Netflix on May 12.

They go over Stone's quixotic life including how he mastered the political dark arts in the 1970s while working on Nixon's Committee to Re-Elect the President, nicknamed CREEP.

As a result Stone became the youngest person to be called to testify before the Watergate grand jury, though it did little to stop his rise.

During the 1980s his lobbying firm that he founded with Manafort became known as the 'Torturer's Lobby' because of their work for brutal dictators that earned them a fortune.

The documentary explains how Stone and his associates developed Political Action Committees to circumvent fundraising rules; they are now the biggest source of unregulated money in politics.

In 1996 Stone was banished from Republican party when it emerged he and his second wife had been placing adverts for partners for swinging, a scandal that he initially denied then later admitted.

Stone has written several books and runs a website, Nowadays he regularly appears on shows like InfoWars where he promotes conspiracy theories, often involving the Clintons.

Stone is being investigated by the FBI because he has admitted he communicated with the hacker known as Guccifer 2.0, whom the intelligence agencies have called a Russian agent.

He also said that he communicated with Assange before Wikileaks released the Democratic party emails.  Stone has called it a 'perfectly legal back channel' with Assange.

Stone has offered to testify before the House intelligence Committee, which is investigating the interference in the US election along with the Senate Intelligence Committee and the FBI.

During the film journalists and commentators back up Stone's claim that he is the one manipulating Trump.

Jeffrey Toobin, a CNN legal analyst and New Yorker contributor, says that 'in many respects Roger Stone created Donald Trump as a political figure'.

He describes the Trump candidacy as a 'pure Roger Stone production' and that the election was the 'apotheosis' of his behind the scenes work.

Toobin says: 'The rest of us looked at Trump and saw somebody who is vulgar and impolite, Roger looked at him and said that this is somebody that voters might like'.

The opening of the film is Trump's acceptance speech at the Republican National Convention last year, during which Stone waves to the crowd as if he were the candidate accepting the nomination and not Trump.

Fox host Tucker Carlson claims that Stone brought Manafort into Trump's campaign specifically to force out Corey Lewandowski, the President's former campaign manager.

Carlson says: 'Trump is hard to guide, he spits the bit out, he doesn't want to be driven at all but Roger has had as much influence on the campaign as anyone.'