A newly released file on the highly-publicized disappearance of British girl Madeleine McCann is "gold dust" and could lead to a breakthrough in the case, her parents' spokesman told Sky News.

McCann spokesman Clarence Mitchell said the family is disturbed that information on possible sightings of Madeleine is only now emerging, after sitting in a box since 2008 when the case was closed by Portuguese police.

SLIDESHOW: Where Is Madeleine McCann?

"The McCanns have been tearing their hair out for a long time, they're very frustrated this information has been sitting in a file since July 2008," Mitchell told Sky News.

The files reportedly contain hundreds of pages of information, including CCTV images of a young girl with an appearance similar to Madeleine being led into a New Zealand supermarket in 2007, according to Sky News.

Madeleine was three years old when she disappeared from her family's rented lodging in Portuguese resort town, Praia da Luz, on May 3, 2007. Her parents were eating dinner with friends nearby.

The new evidence became public after several newspapers applied to the state prosecutor in the Algarve, Sky News crime correspondent Martin Brunt said.

One report allegedly mentions a British man named "George" who spotted a young, seemingly distressed blonde girl being dragged along a road to Faro airport in Portugal on the night Madeleine went missing, Sky News reported.

Another report allegedly details how a young girl who looked like Madeleine was seen being held at gunpoint on a French motorway by a half-naked man in August 2008, according to Sky News.

"This information is gold dust to them. Kate and Gerry need all of it and they want a full review of all the information it contains," Mitchell told Sky News.

"Our investigators are working at times with one hand tied behind their back.

"Any leads must come through Portugal but they must come to Kate and Gerry," Mitchell was quoted by Sky News.

Click here for more from Sky News.