Speaking about the appeal, Mr Wolters said: “Ultimately, we cannot influence the decision because it is not related to the McCann investigation.
“This does not affect our investigations, but of course we would like to know where our suspect is.
“As long as he is in custody, we know this.”
Last week German police reportedly discovered the remains of a hidden cellar among foundations of a former cabin following a three-day search of a garden plot on the outskirts of Hanover.
Scotland Yard maintain their active investigation into Madeleine’s disappearance, Operation Grange, is a missing person inquiry as there is no “definitive evidence whether Madeleine is alive or dead”.