He is one of two suspects who are currently the focus of teams of detectives in Portugal and the UK, Sky News reported.
The man was on remand in prison in Germany when police there decided to alert the Portuguese team which is working with Scotland Yard on the Madeleine case.
It has led to a boost in funding and manpower for the Portuguese detectives, who are based in Porto.
The suspect is thought to have been living on the Algarve Coast in Portugal when Madeleine vanished 12 years ago.
He had not been a suspect at the time, though many alleged pedophiles were investigated and eliminated.
The development comes at a time of renewed optimism in the small Scotland Yard team, which has asked the UK’s Home Office for a whole year of funding to keep its part of the investigation going.
In the past two years, it has restricted its government funding requests to six months at a time.
Metropolitan Police Commissioner Cressida Dick said, "We have active lines of inquiry and I think the public would expect us to see those through. A very small team continues to work on this case with Portuguese colleagues."
Madeleine was nearly four when she disappeared from the apartment as her parents and friends dined nearby in Praia da Luz on May 3, 2007.
Portuguese police abandoned their investigation after 15 months after finding no evidence of what happened to her.
They reopened it in 2012, before Scotland Yard was asked to investigate, too. The two forces worked separately at first, but now share information.
Madeleine's parents Kate and Gerry McCann insist their daughter could still be alive, in the absence of any evidence she has come to harm.
In a statement on the 12th anniversary of her disappearance, they said, "As much as we'd like to fast forward the first couple of weeks of May, there's no getting around it. The months and years roll by too quickly.
"Madeleine will be 16 this month. It's impossible to put into words just how that makes us feel.
"There is comfort and reassurance though in knowing that the investigation continues and many people around the world remain vigilant."