Although numerous suspects have previously emerged as part of the lengthy police investigation, the McCann family spokesman, Clarence Mitchell, said that "it looks like there is something different this time", in an allusion to the evidence.

"In more than 13 years I've been working with the McCann family, I don't remember the police being so specific about a suspect," Mitchell told Sky News.

Madeleine McCann was just three years old when she disappeared on May 3, 2007, when she was on holiday with her parents in Praia da Luz.

UK and German authorities revealed on Wednesday that the suspect I question is 43 years old and is currently in prison in Germany for another crime, and that the suspect frequented the Praia da Luz area at the time the McCanns' oldest daughter disappeared .

Mitchell said the police wanted to obtain very specific details about the German citizen's movement in 2007, notably regarding the phone calls he received the night of Madeleine's disappearance and the fact that he changed his car registration the following day "

Hans Christian Wolters, a prosecutor in Braunschweig, Germany, told reporters that investigators are working on the assumption that Madeliene McCann is dead, admitting that the 43-year-old German citizen is suspected of murder.

"We assume that the child is dead," said the German investigator.

The police described the suspect as being Caucasian, thin and with blond hair, and that he had a caravan in the Algarve in 2007. It is suspected that he travelled through the resort area in the days before and after the date of Madeleine’s disappearance.

Christian Hoppe of Germany's Federal Criminal Police Department revealed to the German public broadcaster ZDF that the suspect is currently imprisoned in Germany for committing a sexual crime and that the detainee has now lived in Portugal for several years and has two previous convictions for "sexual abuse of girls”.

Hoppe said the German police did not rule out that there had been a sexual reason, considering that he had decided to kidnap the child after initially breaking into the McCanns' apartment with the intention of stealing.

Hans Wolters declined to give further details of the suspect's identity in order not to jeopardise the ongoing investigation, although the German press has named him as Cristhian B.

Wolters' description fits that of a 43-year-old man who was convicted in December 2005 for raping an American woman, who was 72 at the time, and the crime was committed in an apartment in Portugal, according to press reports.

The detainee - now a suspect in the McCann case - denied the charges during the American's rape trial and the case is currently on appeal.

Hoppe, for his part, mentioned that the suspect lived between Lagos and Praia da Luz, having been regularly in the Algarve region between 1995 and 2007.

Meanwhile, police in Britain, Germany and Portugal launched a new joint appeal on Wednesday aimed at obtaining more information, namely on the suspect's two vehicles - a Volkswagen van and a Jaguar.

Police are also looking for more information on two Portuguese phone numbers, including one believed to have been used by the suspect on the day of Madeleine's disappearance.

The McCanns spokesman said that Kate and Gerry McCann: “Remain hopeful that she can still be found alive. They never gave up on that hope, nor will they, until they are presented with any indisputable evidence to the contrary. They say that whatever the result of this line of investigation, they need to know the result, to find peace ".