Scotland Yard detectives from Operation Grange will sit in on the questioning, which will be conducted by Portuguese police.
Four new suspects are to be brought in for questioning, reportedly including two Russian businessmen.
The suspects have been given ‘arguido’ status- which means that they are formal suspects under Portuguese law.
Eight witnesses will also reportedly be questioned, some of which are alleged to be burglars who carried out raids in Praia da Luz around the same period as Maddie’s disappearance.
Four-year-old Maddie disappeared from her parent’s holiday apartment in April 2007, and despite a massive search operation no clues were discovered to solve her disappearance.
Maddie’s parents, Kate and Gerry McCann, recently travelled to Portugal to speak in court against a detective working on the initial search for their daughter.
April Jones gran on Maddie McCann: 'Her parents don't want her to be found'
The former police detective wrote a book suggesting that Maddie’s parents covered up her death.
A spokesman for the couple said: “It is a matter for the Metropolitan Police what they do and when they do it.”
Kate and Gerry McCann prepare for significant news on Maddie case
British police have spent the past few weeks in Portugal searching scrubland surrounding the Praia da Luz resort and working on many leads in the investigation.