"The cult of celebrity is pernicious and it leads people to go blind and parents to do stupid things," says Dan Reed, director of a new Michael Jackson documentary.

His film, Leaving Neverland, first made headlines in January, when it was considered so graphic that mental health professionals had to be on hand at a screening.

Showing at Sundance Festival, the four-hour film featured the testimonies of Wade Robson and James Safechuck, who say they were sexually abused by the singer as young boys in the 1990s.

The Jackson estate has denied the allegations and made a number of attempts to discredit the film, calling it "an outrageous and pathetic attempt to exploit and cash in" after the singer's 2009 death.

But Reed tells the BBC he hopes his film will "make parents think twice about trusting strangers and will make people think twice about idolising a celebrity".

With a week until its release on Channel 4, Reed has spoken about the power of the testimonies of Robson, 36 and Safechuck, 40.

He says it took "a period of time" to believe them both.

"I interviewed Wade for three days and James for two days.

"It's the cumulative impression that they made, how open they were, how consistent their accounts were, how nothing that I discovered later when I did in-depth research contradicted what they said."

Reed says he also spent a lot of time looking into the cases of Jordan Chandler and Gavin Arvizo, who brought legal action against Jackson whilst he was alive in 1993 and 2004.

Chandler's case was settled out of court, whilst Jackson was found not guilty on all charges during Arvizo's case.

Reed continued: "There was also plenty of evidence in sworn statements by members of Jackson's staff, etc, that corroborated aspects of what they [Robson and Wade] told me.

"There's a huge amount of work we did over two years to try and test everything that they said and I never found anything that cast any doubt."

'I salute their courage'
As part of the documentary, the families of Robson and Safechuck were interviewed, including their mothers, fathers and siblings.

Their interviews detail from the first time the boys met Jackson - Robson at a concert in Australia and Safechuck at a Pepsi commercial shoot - up until the present day.

Reed says "the accounts of their [Wade and James] mothers and families were also very consistent and supported everything they said."

He added: "I found the mothers entirely believable as well.

"I mean, for a mum to go on the record and admit that she had delivered her child into the clutches of a predatory paedophile is not a nice thing to have to admit for any mum.

"I salute their courage in sitting down and laying bare how they felt when telling you the whole story."

"I can't imagine any circumstances in which a mother would sit down and make that up - it's the most humiliating, appalling thing to have to admit as a mother you were in the next room while someone was raping your child for years and years."

Reed also says he had the same feeling about Wade and James too, and said "you wouldn't make up such graphic, sexual descriptions" when describing their sexual encounters with Jackson.

As boys, they both spent time at Jackson's Neverland ranch, claiming that they had shared beds with the singer.

"If they weren't said with such dignity, these things would be deeply humiliating for a grown man," he added.

HBO, who made the film in partnership with Channel 4, are currently being sued by the Michael Jackson estate for breaking a reputation clause in an old contract.

The family maintain that Jackson is innocent and has been proven so in a court of law.

Reed says that when making the film, he had "no contact with the estate or the family before making the film".

"The views of Jackson and the views of his lawyers, and their rebuttals, their denials are plentifully represented in the film," he adds.

"We've given a lot of space to allow them to deny and we've even put fans in saying horrible things about Wade.

"We consider that we've given their views plenty of space and adequate representation in the film, it's not a one sided film at all and you can see the Jackson side.

"They still deny that any sexual abuse took place and that view hasn't changed since the last time I checked."

When Jermaine Jackson was asked about the film on ITV's Good Morning Britain, he asked people around the world to "let this man rest" and said his family were "tired" of defending Michael.

Reed's response to this was to say "we're not digging up Michael Jackson".

"What we're doing is telling the stories of two of his victims and they're very much alive and well. They deserve to have their say and to be heard.

"I think the #MeToo movement has changed the landscape - the family has hit out in a very old-fashioned way, which is to say it's all about money.

"They haven't received a penny, nor will they - they have no financial interest whatsoever in the film and we never offered any."

'The cult of celebrity'
In light of this film being released, comparisons have been made with the allegations that have faced singer R Kelly.

The singer has been accused of sexually abusing a number of women, with some underage. But for the large part his music has remained popular despite such allegations, which he has denied.

Reed says that the reason people like Jackson and Kelly have not been scrutinised is because "people are dazzled by talent and status, wealth, reputation".

He adds: "Especially when you're very young and your idol is an incredible dancer or singer, you translate their talent into goodness, you translate their talent into the type of human being they are.

"You assume that they're a nice person and unfortunately that is not the case.

"We have to be more sceptical and we have to challenge fame, celebrity and power more than we have in the past."