Madeleine McCann Netflix: Here's what we know about the documentary.

On the evening of May 3, 2007, Madeleine McCann disappeared while on a family holiday.

She was just three years old.

On vacation in Portugal, the last time Madeleine’s parents, Kate and Gerry McCann, saw their daughter was in a hotel room, just before they went out for dinner with friends nearby.

Twelve years later, there has never been a credible sighting of Madeleine. But photos of the wide-eyed little girl have circulated for years, making her one of the most recognisable missing children in the world.

The McCann family has never lost hope that their daughter, who would have turned 15 in May this year, is still alive.

Now, Netflix has made a documentary investigating the disappearance of Madeleine McCann.

Netflix previously confirmed to RSVP Live the documentary surrounding Madeleine's disappearance was in production, but have remained tight-lipped since. However, new details have emerged, with rumours that it could be released within the next two weeks.

It's understood that Madeleine's parents, Kate and Gerry, won't take part in the documentary with the Metropolitan Police's investigation still active.

A source said to be close to the producers has told the Daily Mail, "Everyone everywhere is fascinated by the Maddie story.

"We would have welcomed the opportunity of working with the McCanns directly but they informed us they couldn’t and wouldn’t consider taking part while a police investigation into their daughter’s abduction is ongoing.

"But we have interesting new interviews with people close to the inquiry and we believe we can give justice to this unbelievably tragic story."

It's also reported that Netflix originally intended for it to be an eight-part series, however there's a suggestion that it will now either be compiled into just a one off documentary, or be in two parts.

A friend of the McCanns also told the Daily Mail: "We understand it is a serialised drama but neither Kate, Gerry nor their holiday friends and main players have co-operated in any shape or form.

"And we have no idea who the actors are. We believe it is coming out very soon, within the next two weeks and before the next anniversary."

They continued: "Netflix had been hoping to screen it last year but the project took them a lot longer than expected".

It has reportedly cost the Oscar-winning streaming service £20 million (about $37 million AUD).

It's not known if retired Portuguese detective Goncalo Amaral has taken part in the documentary, but it's understood that he was approached by producers.

The former detective has accused Madeleine's parents of covering up their daughter's death by staging an elaborate abduction, in his book The Truth of the Lie. Amaral and Madeleine's parents are involved in an ongoing legal battle.

The friend of the McCann family also told the Daily Mail that, "Their lawyers will be keeping watch for any potentially libellous material".

The documentary will follow a number of true crime series created by Netflix, including Conversations With A Killer: The Ted Bundy Tapes, Abducted in Plain Sight and Making A Murderer.