"The searches are linked to our investigation of the Madeleine McCann case," Julia Meyer, a spokesman for the Braunschweig attorney general's office, who is investigating the disappearance of Madeleine McCann and other children related to the suspect Christian B, 43, who is being held in Germany after living in the Algarve when Madeleine disappeared.

The spokeswoman did not provide further details on the steps that led investigators to use an excavator, according to the local newspaper Hannoversche Allgemeine, which recalls that the suspect once lived in Hannover.

The case has seen new developments since the beginning of June, with the identification of this new suspect, Christian B., a German paedophile previously convicted of raping an elderly woman in Portugal and currently serving a prison sentence in Germany.

German researchers are convinced that Madeleine McCann, who was three years old at the time of her disappearance in Portugal in 2007, is dead.

The Braunsschweig prosecutor's office says it has "hard facts or evidence" that supports the thesis that Madeleine McCann is dead, but not "forensic evidence" since the child's body was never found.

The suspect, Christian B., is being held in Kiel, northern Germany, for other crimes.

In 2007, the suspect lived a few kilometres from the village of Praia da Luz, where Madeleine McCann disappeared.

Christian B.'s defence lawyer, quoted by the German media, refutes any involvement of his client in the disappearance of children.

According to local media outlets, German investigators discovered children's clothing in a caravan that belonged to the suspect and discs containing thousands of images of paedophile content.

As part of the process in which he is serving time in Germany for other crimes, the suspect asked to be released on parole, but the request has been rejected under the influence of the Braunschweigh Prosecutor's Office, which believes that Christian B., is the key to the disappearance of Madeleine and other minors in Germany.