Portuguese detectives failed to ask for any follow-up investigation after a young girl resembling Madeleine McCann was caught on CCTV in New Zealand, it emerged today.
New Zealand Police said their file remained open following the possible sighting of the missing child in Dunedin in December 2007.
Details of the incident are included among 2,000 pages of previously secret case documents held by Portuguese police which were released to British newspapers today.
They detail dozens of possible sightings of Madeleine after she disappeared from her family's holiday flat in Praia da Luz, southern Portugal, in May 2007, just before her fourth birthday.
New Zealand Police confirmed today they investigated a report that a woman saw a little girl who looked just like her in a Dunedin shop.
Officers obtained CCTV footage of the child hand-in-hand with a stout man wearing a white t-shirt and black shorts.
Inspector David Campbell, Acting Southern District Commander, said in a statement: "Police were unable to obtain any further information or ongoing lines of inquiry.
"The file was forwarded to Interpol and this is correct procedure under international agreements. The lead jurisdiction, in this case Portugal, directs how the case progresses and has not asked NZ Police for any follow-up to date.
"The file has remained open ever since."
Other leads in the newly-released Portuguese police dossier include a report of a small blonde girl being dragged along the road to Faro airport in the Algarve - an hour's drive from Praia da Luz - on the night Madeleine vanished.
Another details how a young girl who looked like the missing child was seen being held at gunpoint on a French motorway by a half-naked man in August 2008.
All the information should be released to the private detectives hired by Madeleine's parents, Kate and Gerry McCann, their spokesman Clarence Mitchell said.
Mr Mitchell said: "Kate and Gerry have made it clear that they were shocked to see the lack of follow-up work done by the Portuguese police since the investigation was shelved.
"All the information in these files must go to the private investigators as they are the only people still looking for Madeleine."
The McCanns, both 41 and from Rothley, Leicestershire, spoke last month of their frustration that police had failed to investigate new leads in their daughter's disappearance.
Mr McCann said: "There are certainly instances where information which we think is very credible and worthy of further investigation has not been actioned.
"We're gutted, it's absolutely shocking and difficult. We're trying our absolute best, Madeleine's still missing, and as we say the perpetrator's still there.
"We're not saying they are the leads that will result in finding her. But if you don't investigate information when it comes in, you will never solve it."
His wife added: "It's heartbreaking, to be honest."