The lengthy document was posted on a newspaper website the day after prosecutors shelved the case and formally lifted the suspect status of the little girl's parents, Kate and Gerry McCann.
The couple's lawyers in Portugal are still awaiting official notification that they can now examine the police files in detail.
It is hoped they will gain access to the dossier, thought to stretch to 13 volumes, by the end of this week.
A 57-page report dated June 20, 2008 and written by an Algarve-based inspector with the Policia Judiciaria - Portugal's CID - was placed on the website of the Portuguese newspaper Expresso today.
McCann family spokesman Clarence Mitchell criticised the apparent leaking of the document.
He said: "As always we simply will not comment on anything that appears to be from the usual anonymous sources.
"If any elements of the police report are being placed online, that would not only be wrong, you have to ask yourself who is behind it and why.
"Gerry and Kate's lawyers in Portugal will be applying formally for access to the complete file and they will be analysing everything in it in their own time without making elements public at this stage."
The leaked document appears to be a summary of the huge police dossier which was handed to prosecutors at the start of this month.
It details the many leads that Portuguese detectives followed up - including interviews with resort staff, witness sightings and house-to-house inquiries at 443 properties in the village where Madeleine went missing.
The McCanns, from Rothley, Leicestershire, hope the opening of the files will provide fresh leads in their own private investigation into their daughter's whereabouts.
Mr and Mrs McCann will "bide their time" before speaking out on the police inquiry into Madeleine's disappearance, Mr Mitchell said today.
Legal action against the Portuguese authorities is an option, but that is not the couple's priority, he added.
Mr Mitchell said: "It's going to be a long, slow process, both for the lawyers in examining the volumes and for Kate and Gerry to be informed of their contents and whether there's any need for legal redress.
"The priority has always been finding Madeleine so the investigative work is first and foremost.
"If there are any leads from the files, for instance new sightings, that's what the private investigators will focus on in the first instance.
"The question of legal action remains an option but that is not the priority right now. It is something Kate and Gerry will take advice on from the British and Portuguese lawyers."
Madeleine was nearly four when she vanished from her family's holiday apartment in the Algarve resort of Praia da Luz on May 3 last year as her parents dined with friends nearby.
The leaked police report reveals that detectives made the McCanns "arguidos", or formal suspects, in September in the light of sniffer dog searches and initial DNA test results.
This was because their inquiries had flagged up the "slightest chance of their involvement with a possible corpse" in their holiday flat and hire car, it says.
The couple denied the allegations in their interviews, the report notes.
A "cadaver dog", trained to sniff out dead bodies, picked up a scent in the McCanns' apartment and on clothes belonging to Mrs McCann and Madeleine, according to the document.
It also scented death on the key of the Renault Scenic hire car rented by the McCanns 24 days after the little girl went missing, it says.
A second dog apparently detected blood on the key and in the boot of the car, as well as in the apartment.
Preliminary forensic analysis on samples recovered from the McCanns' hire car raised the possibility of a match with Madeleine's DNA profile, according to the leaked report.
But the final results could not match the material to any particular person - or even establish whether it was blood or another type of body fluid.
The document also suggests that Madeleine was left crying in her family's holiday flat for more than an hour while her parents were out, two days before she went missing.
Pamela Fenn, a retired British ex-pat who lives upstairs from the McCanns' apartment in Praia da Luz, said she heard the child wailing from about 10.30pm to about 11.45pm on May 1 last year.
Mrs Fenn said Madeleine only stopped crying after she heard the sound of the door when her parents came back.
This "calls into question" the McCanns' insistence that they checked on their children every half an hour, the report says.
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