“I can confirm that the search is being carried out in connection with our investigations into the Maddie McCann case,” Brunswick prosecutor Julia Meyer told AFP, when asked about the move first reported by local newspaper Hannoversche Allgemeine Zeitung.
Police began searching the site in the early hours of Tuesday morning, clearing trees and using an excavator to dig up the area.
Several police vehicles were parked along the side, while officers with spades were shovelling in the cordonned-off zone. Police also used a forklift to transport large stones out of the area.
Meyer gave no details of how the plot was connected to the case or what they were hoping to find.
Police raised hopes in June that the mystery over the 2007 disappearance of three-year-old “Maddie” could finally be solved when they revealed they are investigating 43-year-old German Christian B.
Police revealed in June that they were investigating a 43-year-old German man over the 2007 disappearance of three-year-old “Maddie”, saying they believe he killed her.
Madeleine went missing from her family's holiday apartment in the Portuguese holiday resort of Praia da Luz on May 3, 2007, a few days before her fourth birthday, as her parents dined with friends at a nearby tapas bar.
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Despite a huge international manhunt, no trace of her has been found, nor has anyone been charged over her disappearance.
The suspect, who was not named by police but identified by German media as Christian B., has a history of previous sex offences including child sex offences and rape. He is currently serving a sentence for drug trafficking in Kiel.
He has applied to be released early on probation after having completed two-thirds of the sentence, with a decision still pending.
A court in Brunswick had separately sentenced Christian B. to seven years in prison last December for an assault against a 72-year-old American tourist in 2005 — in the same seaside village of Praia da Luz where Maddie went missing.
But that sentence has not yet been finalised pending an appeal by the defendant's lawyers over extradition technicalities.
According to police, the suspect lived in the Algarve region of Portugal between 1995 and 2007.
He made a living doing odd jobs in the area where Madeleine was taken, and also burgled hotel rooms and holiday flats.
German prosecutors said in June they had “concrete evidence” that Madeleine is dead, despite British police continuing to treat her disappearance as a missing persons case.
However, despite repeated appeals for information, prosecutors have no forensic evidence and have so far not filed any formal charges.
In a recent TV appeal, investigators said they were looking for the owner of a Portuguese mobile phone number that Christian B. had called in May 2007.
Following the stunning revelation from German police that Christian B. could be linked to the missing British girl, investigators elsewhere in Europe were once again looking at cold cases of missing children or teens.
Belgium reopened an investigation into the 1996 murder of a German teenager Carola Titze, 16, who was found dead and mutilated in July 1996 in the resort town of De Haan on the Belgian coast.
In the Netherlands, investigators are taking a closer look at the unexplained disappearance in 1995 of Jair Soares, a seven-year-old Portuguese child.
While living in Hanover, Christian B. received fines for forgery in 2010 and for theft in 2013, according to a report by German news agency DPA.
He split his time between Germany and Portugal from 2013 to 2015, the report said, citing prosecutors in Hanover.
At the end of 2012, he reportedly opened a small shop in Brunswick with his then girlfriend.
After they split up, he continued to run the shop alone until he gave it up 18 months later, along with the adjacent apartment.
Investigators have said Christian B. would only be questioned in connection with the Madeleine McCann case after the investigation is concluded, so that they could present him with the findings of the probe.
By Marion Payet and Femke Colborne