An appeal by UK police has generated almost 400 tips in the days since authorities said they were investigating a new suspect in the disappearance of Madeleine McCann.
The 43-year-old convicted German child sex offender, who is serving a jail sentence in his home country, has been named in reports as Christian Brueckner.
A Metropolitan Police spokesman said: "The Op Grange team have had just short of 400 pieces of information through, in calls and emails."
Operation Grange refers to the force's active investigation, which the spokesman said police still considered a missing person inquiry because there was no "definitive evidence whether Madeleine is alive or dead".
Meanwhile, German prosecutors are reportedly examining possible links to the disappearance of two other children.
They believe Madeleine -who was nine days from her fourth birthday when she vanished from a holiday apartment in Praia da Luz, in Portugal's Algarve, on May 3, 2007 - is dead.
They are now investigating the suspect over her presumed murder.
German news websites have now reported that authorities have contacted the family of Rene Hasee, who went missing in 1996.
According to reports the six-year-old boy, from Elsdorf, Germany, went missing from a beach while on holiday with his family in the Algarve.
An investigation has also been opened into whether the suspect was involved in the disappearance of Inga Gehricke.
She was five years old when she vanished from a forest in the Saxony-Anhalt region of German on May 2, 2015.
Prosecutors in the northern German town of Stendal have confirmed they are probing possible connections between the cases of Madeleine and Inga.
But they said the man, who has been partially identified as Christian B by local media due to the country's strict rules on the naming of criminals, was not currently a suspect.
Meanwhile, a UK newspaper reported that a witness had identified the suspect as a man she saw acting suspiciously outside the McCanns' apartment.
According to the 'Sun', the British woman - referred to as a "credible witness" - said "that's the man I saw" when shown a picture of the suspect.
The woman reported the sighting within hours of Madeleine's disappearance, the newspaper added.
The latest developments come after claims, originally reported by Sky News, that the suspect confessed his part in Madeleine's disappearance to a friend as they watched a TV news report on the case in a German bar on the 10th anniversary of her disappearance.
Scotland Yard said his name was already known to its investigation, but he did not become a suspect until after information was received as a "direct consequence" of a 2017 appeal.
The suspect is reportedly serving a seven-year prison sentence in the German port city of Kiel for the rape of a 72-year-old American woman in Portugal in 2005 after his conviction at Braunschweig District Court last December.
'Der Spiegel' reported his criminal record contains a total of 17 entries, including a conviction for the sexual abuse of a child in 1994 when he was aged 17, and a 2016 conviction for abusing another child and possession of child pornography.
Madeleine's parents, Kate and Gerry McCann, from Leicestershire, welcomed the latest police appeal in a statement, saying: "We will never give up hope of finding Madeleine alive."
Their spokesman, Clarence Mitchell, said: "They certainly will be encouraged to know the appeal is yielding results already and hopefully within that there will be crucial bits of information the police can act upon."