German police have a European warrant, which has been approved by Portuguese prosecutors, will allow them to conduct searches on private land. This week's search is expected to span across 21 different plots of land.
Officials have not disclosed if they are conducting this latest search in Portugal based on any new information, making it appear as if they are taking one last look in places where evidence or a body could have been hidden
Portuguese authorities have also named Brückner as a formal suspect, or "arguido". They said they will hand over any evidence seized in the latest search to German authorities.
The Met Police, which said this week that it was aware of the searches being carried out by German police in Portugal, continues its investigation into Madeleine's disappearance.
The case, known as Operation Grange, has been ongoing since 2011 and has cost around £13.3m to date.
On the night Madeleine disappeared, her parents had been at dinner with friends at a restaurant a short distance away from the ground-floor apartment she and her younger twin siblings were asleep in.
Her mother, Kate, discovered she was missing at around 22:00.
A German documentary in 2022 found evidence that Brückner occasionally worked at the Ocean Club as a handyman, while German prosecutors have also linked his mobile phone data and a car sale to their case against him.
Madeleine's parents marked the 18th year anniversary of her disappearance last month, saying their "determination to leave no stone unturned is unwavering".