Kate and Gerry McCann hold an age-progressed police image of their daughterin the fifth anniversary of the disappearance in 2012. Picture: Getty.

The remote area around the Ocean Club resort in Portugal, where the three-year-old British girl vanished from her holiday apartment in 2007, has been described as the perfect place to hide a body, those connected to the case say.

“It’s almost impossible,” retired Scotland Yard detective Colin Sutton told Channel Seven Sunday Night program of Praia da Luz, in the Algarve region of Portugal, where the McCann’s were staying.

“It would be impossible without specific information or intelligence which enabled you to focus a search in a particular area.

“It is a large area, with a very low population, of scrubland, of ancient wells. There are areas there where humans probably don’t go from one year to one decade even to the next. It would be really easy to secrete something there and be really confident that it wouldn’t be found.”

The area is home to as many as 500 wells and has been described by forensics expert Professor Dave Barclay as “the most hide-a-body-able place I’ve ever been in my life.”

“I’m sure the reason this case has run as long as it has and still arouses fantastic interest even now is because every single one of the explanations, the possible explanations is implausible, and yet we know one of them must be correct,” he told the program.

“It might be solved if Madeleine’s body is found and there is evidence either on the body or in the location where the body is found that would point to somebody but otherwise, I don’t think it will ever be solved

“There is just no physical evidence whatsoever that we can use at this time, even to eliminate some of the theories.”

Madeleine McCann’s body could be at the bottom of one of hundreds of ancient wells.Source:AP

A local reporter said bones might be found “five to 10 years from now” only if a person who lived in the area decided to clear out one of the hundreds of deep wells to put it back in operation.

In two fresh theories aired by the program, Detective Sutton said an employee of the holiday resort where Madeleine was staying could have the information investigators needed to unlock the mystery.

Professor Barclay also suggested the little girl may have wandered out of the apartment looking for her parents, who were dining at an adjoining tapas bar, and could have been run over by a car. The driver may then have tried to dispose of her body to cover up the accident.

“There is an employee, somebody who worked within the Ocean Villas (sic) complex who it is felt has some information or some knowledge which might be of assistance,” Detective Sutton said.

Madeleine McCann would be 14 on May 12. Since her disappearance, there have been 8685 reported sightings of her across 101 countries, according to the program.

“People say to me ‘Maybe she’s been stolen to order’ (and I say) ‘Don’t be ridiculous,” Madeleine’s father Gerry McCann said of the theory that she had been abducted as part of a sex trafficking operation.

“But actually compared to everything else that’s happened, that’s a possibility.”

Kate and Gerry McCann said they were reluctant to go on holiday to Portugal in the first place.Source:AP

The program claims a wave of crime on the Algarve in the lead up to Madeleine’s disappearance had been whitewashed by Portuguese authorities, including 12 incidents of an intruder breaking into the properties of UK families within a 60 kilometre radius of the McCann holiday villa, half involving a man hopping into bed with little girls.

Nannies working at the resort had also reportedly been given “rape alarms” and told it was not a safe place.

“The fact that there were random paedophiles going around taking children out of holiday apartments probably would have been quite a disincentive to families turning up for their holidays,” Professor Barclay said, suggesting it might also explain why UK police had not given up the $20 million investigation.

Investigators say an employee at the Ocean Club apartments may have crucial information.Source:AFP

Gerry McCann described allegations made by Portuguese detective Goncarlo Amaral that British intelligence agency MI5 know what happened to Madeleine but are covering it up as absurd.

“It’s caused a lot of upset and has damaged the search,” he said.

Madeleine’s mother Kate told the program she had initially been reluctant to go to Portugal on holiday because she didn’t want to travel with three small children — Madeleine and her twin baby siblings — but had been convinced by friends.

The McCanns cling to the hope that their daughter “might come out of the woodwork” like other children who have been abducted and held against their will for years and say they will never give up the search.

Kate and Gerry McCann hold an age-progressed police image of their daughterin the fifth anniversary of the disappearance in 2012. Picture: Getty.Source:Getty Images