Permission has been granted for a "field operation" to begin on a section of private land, sources have said.
The Met Police, which is leading the investigation, declined to comment.
Met detectives are understood to have left Portugal after spending two days with Portuguese police in the Algarve.
BBC reporter Richard Bilton, in Praia da Luz, said Portuguese authorities had so far granted permission to begin a search on the land, which could begin in "days" or "weeks".
He said he had been told him that British teams want to conduct more searches, but have yet to make an official request, which could take "weeks" to process.
It is thought that Metropolitan Police detectives have discussed a timetable for investigative work that Portuguese police will carry out for the British team, he added.
The development comes after reports suggested search teams were expected to start excavating sites in the Praia da Luz resort where Madeleine - then aged three - went missing on 3 May 2007.
Met Police Assistant Commissioner Mark Rowley this week said "activity" was expected to begin in Portugal "in the coming weeks".
It also comes after Madeleine's parents, Kate and Gerry McCann, posted a statement on the Find Madeleine website on Thursday criticising "media interference" over newspaper speculation in the case.
They warned they were "dismayed" at speculation which could "potentially damage and destroy the investigation altogether".
They added: "There is an on-going, already challenging, police investigation taking place and media interference in this way not only makes the work of the police more difficult."
"As Madeleine's parents, this just compounds our distress," they added.
The seventh anniversary of Madeleine's disappearance was marked on Saturday.
Scotland Yard launched a fresh investigation - codenamed Operation Grange - into Madeleine's disappearance last July.
In March, British police then said they were seeking an intruder who sexually abused five girls in Portugal between 2004 and 2006.
Detectives said the attacks happened in holiday villas occupied by UK families in the Algarve.
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Portuguese authorities have granted permission for one site in the town of Praia da Luz to be examined as part the investigation into Madeleine McCann's disappearance, the BBC understands.