German child sex offender living in campervan prime suspect in Madeleine McCann case

The suspect, who has not been named, is described as white with short blond hair, possibly fair, and about 6ft tall with a slim build at the time she vanished on May 3 2007.

Christian Hoppe, from Germany's Federal Criminal Police Office (BKA), told the country's ZDF television channel the 43-year-old is serving a prison sentence for a sex crime and has two previous convictions for "sexual contact with girls".

Mr Hoppe said German police have not ruled out a sexual motive, but added that the suspect may have broken into an apartment in the Ocean Club complex in Praia da Luz - where Madeleine was on holiday with her parents, Kate and Gerry McCann, and her twin siblings Sean and Amelie - before spontaneously kidnapping her.

The German national is known to have been in and around the area on the Algarve coast at the time Madeleine went missing shortly before her fourth birthday.

A half-hour phone call was made to his Portuguese mobile phone around an hour before Madeleine is believed to have gone missing.

The suspect has been linked to an early 1980s VW T3 Westfalia camper van - with a white upper body and yellow skirting, registered in Portugal - which was pictured in the Algarve in 2007.

Scotland Yard said he was driving the vehicle in the Praia da Luz area in the days before Madeleine's disappearance and is believed to have been living in it for days or weeks before and after May 3.

He has also been linked to a 1993 Jaguar XJR6 with a German number plate seen in Praia da Luz and surrounding areas in 2006 and 2007.

The day after Madeleine went missing, the suspect had the car re-registered in Germany under someone else's name, although it is believed the vehicle was still in Portugal.

Both vehicles have been seized by German police.

Scotland Yard is launching a joint appeal with the BKA and the Portuguese Policia Judiciaria (PJ), including a £20,000 reward for information leading to the conviction of the person responsible of Madeleine's disappearance.

The Met's investigation has identified more than 600 people as potentially significant and were tipped off about the German national, already known to detectives, following a 2017 appeal 10 years after she went missing.

She vanished shortly before her fourth birthday and would have turned 17 last month.

German police are treating her disappearance as a murder investigation but the Met's Operation Grange, launched in 2013, has always considered the case a missing person inquiry.

A statement from Madeleine's parents, read by Detective Chief Inspector Mark Cranwell, said: "We welcome the appeal today regarding the disappearance of our daughter Madeleine.

"We would like to thank the police forces involved for their continued efforts in the search for Madeleine.

"All we have ever wanted is to find her, uncover the truth and bring those responsible to justice.

"We will never give up hope of finding Madeleine alive, but whatever the outcome may be, we need to know as we need to find peace.

"We will be making no further comment in relation to the appeal today.

"We would like to thank the general public for their ongoing support and encourage anyone who has information directly related to the appeal to contact police."