Three newspapers - Correio da Manha, Jornal de Noticias and Expresso - published comments on Tuesday from unidentified police sources saying the 14-month investigation had reached a dead end and is to be ended due to a lack of conclusive evidence.
However, Attorney-General Fernando Pinto Monteiro said in a statement that prosecutors will examine the police report before deciding whether to halt the investigation or undertake further inquiries.
Officials will "determine whether further inquiries are needed or whether the conditions are in place for the investigation to be closed," the statement e-mailed to The Associated Press said.
It said the case file amounted to "dozens of volumes" and noted that the judicial secrecy law covering ongoing investigations, which ensures evidence remains confidential, expires only in mid-August.
Madeleine McCann went missing in Portugal's southern Algarve region during a family vacation in May 2007, a few days before her fourth birthday. Detectives named her parents, Kate and Gerry, and local man Robert Murat as formal suspects in the case. All denied involvement in Madeleine's disappearance.
Closing the case would mean that the official suspects would no longer be under formal investigation.
The McCanns, who have waged an international campaign to find their daughter, returned home to central England with Madeleine's younger sister and brother last September, a few days after they were named as suspects.
Clarence Mitchell, the parents' spokesman, said that if the investigation were to be closed he expected the search for Madeleine to continue.
"The information in their files surely cannot sit on the shelf gathering dust. Kate and Gerry will never give up searching for their daughter," Mitchell said.
He said that if Portuguese police end their inquiry they should hand their files over to the McCanns' private investigators.
"The police themselves must continue looking for Madeleine. We are concerned that if they are to simply shelve the case then what will happen to all of the information in their files? They must be made available to our investigators, who are working extremely hard to find Madeleine," Mitchell said.
The case has drawn global interest. A few weeks after Madeleine vanished, Pope Benedict XVI blessed the McCanns and a photo of their daughter during his weekly general audience at the Vatican. Numerous reported sightings of the blonde-haired girl proved to be false.
British and Portuguese police have cooperated in the investigation. Sophisticated forensic tests on evidence gathered at the resort where the girl disappeared were carried out in Britain.
In April, British police in England, accompanied by Portuguese detectives, re-interviewed the McCanns' friends, who were having dinner with them when Madeleine vanished.