
Mrs McCann was driven to the station in Portimao by her husband Gerry from their rented house in Praia da Luz. He dropped her off at the entrance and gave her a goodbye kiss. Mr McCann will be questioned separately tomorrow. The couple said they were happy to help the police with their investigation into the four-year-old's disappearance.
Sky News Crime correspondent Martin Brunt said police wanted to re-interview the McCanns as witnesses. But he added: "According to the McCann family it appears to be more formal."
Portuguese police called Mr McCann on Monday to request the interviews, specifying that Mrs McCann should be questioned first. It is only the second time she has been formally interviewed by police, the first being on May 4, the day after Madeleine went missing. Detectives have already questioned Gerry McCann twice.
The development comes after officers leading the investigation were given DNA test results.
Sky News has learned vital clues from the results are expected to lead to a significant development.