German investigators are searching a garden in Hanover in connection with the disappearance of Madeleine McCann.
Police began work at the site on Monday and are expected to remain on Tuesday and Wednesday.
Julia Meyer, a press spokeswoman for the prosecutor’s office in Braunschweig, confirmed that the activity was linked to the investigation, but could not comment further.
Local media reports included pictures of an excavator at the scene and officers using shovels.
Madeleine was three when she went missing while on holiday with her family in Praia da Luz, Portugal, on May 3 2007.
German investigators believe Christian Brueckner, 43, killed her soon after abducting her from a holiday apartment in the resort.
Brueckner is in jail in Germany for drug dealing, and is appealing against a conviction for the 2005 rape of a 72-year-old woman, also at Praia da Luz.
He is a suspect in a string of unsolved crimes, reportedly including an attack on a 10-year-old British girl in the resort in 2005, one of a series of incidents where young girls were targeted.
German prosecutor Hans Christian Wolters, who is leading the investigation into Brueckner, previously told the PA news agency that prosecutors have “concrete evidence”, but not “forensic evidence” that Madeleine was killed by the suspect.
He said they may “know more” than Scotland Yard, who are still treating the case as a missing person investigation.
There has also been search activity in Portugal. Earlier this month The Mirror reported that police and divers in the Algarve examined three disused wells around 10 miles from Praia da Luz.