Scotland Yard's "Maddie Squad" are reviewing all evidence including video interviews and witness statements.
A Met Police report, including eight new leads, will make recommendations later in the year. Portuguese officers are expected to reopen the case.
No-one has been arrested since Maddie, then aged three, went missing from an apartment in the Algarve resort of Praia da Luz in 2007.
According to the Daily Star, a source close to the investigation said: "Their attitude is that it is solvable. The approach is very professional. They want definitive answers and are working extremely hard to get to the truth. The investigation is gathering momentum."
Det Ch Insp Andy Redwood is leading 36 detectives and sources say he has an "excellent" working relationship with Portuguese cops.
Leicestershire Police, who worked closely with Portuguese detectives, handed over all evidence on the case to the Yard.
Meanwhile, mum Kate McCann will release the paperback version of her book Madeleine on May 10. She is also expected to attend a reception at Downing Street where David Cameron will back International Missing Children's Day on May 25.