Kate McCann refused to answer 48 questions put to her by Portuguese detectives after being made a suspect in her daughter Madeleine's disappearance, according to police files.

She used her right as an arguido, or formal suspect, to remain silent during part of her interview on 7 September last year. The details came to light after the police files from the exhaustive inquiry, which lasted over 14 months, were made public.

They included pictures from the room where Madeleine, who was nearly four, had been staying during a family holiday in the Algarve resort of Praia da Luz.

In one photograph, the bed in which she was sleeping was seen next to a play pen. Other photos show the view from the apartment's balcony, which looks on to the tapas bar at which the McCanns dined with friends on the evening Madeleine disappeared.

The dossier includes transcripts of interviews with both Kate and Gerry McCann. Officers questioned Mrs McCann about everything from her movements on the night, to her medical specialism and Madeleine's behaviour. They also asked whether she was responsible for her daughter's disappearance.

At one point Mrs McCann refused to answer the question: "Is it true that in England you considered handing over Madeleine's custody to a relative?"

The final unanswered question was: "Did you have any responsibility or intervention in your daughter's disappearance?"

The files show that the only question she did answer was: "Are you aware that in not answering the questions you are jeopardising the investigation, which seeks to discover what happened to your daughter?" She replied: "Yes, if that's what the investigation thinks."

Mrs McCann has always strenuously denied any involvement in Madeleine's disappearance and her arguido status was lifted on 21 July.

The decision by Portuguese detectives to name the McCanns as suspects was said to have been based on DNA tests. However, the records reveal a British scientist had warned the results of the controversial "low copy number" test on a sample from the McCanns' hire car were inconclusive in an email dated 2 September 2007, four days before they were named as suspects.

The expert noted the components of Madeleine's DNA profile were not unique to her.

Lawyers for the McCanns were formally given access to the documents last week. They are hoping for fresh leads that the couple's own team of private detectives can follow up.