Gerry and Kate McCann refused to answer 40 questions when interrogated by detectives about Madeleine's disappearance, Portuguese media claimed yesterday.

Kate was said to have become "nervous" when told experts had discovered blood matching Madeleine's DNA profile.

Several Portuguese papers quoted unnamed police sources as saying Kate became "angry and upset" during her two days of questioning and said police were unhappy at the couple's refusal to reply.

When confronted about the discovery of blood in Madeleine's bedroom, it was claimed Kate gave "evasive replies" before stating "it could be from a wound or a nose".

They wrote: "Kate was informed the blood was Madeleine's - as a corpse. She insisted this was impossible and became nervous."

One paper claims the police "took advantage of the moment of weakness to confront her with the blood stains found in the car hired 25 days after Maddy's disappearance. Kate became upset and stated that she would not answer any more."

It was at this stage that officers said she had to answer their questions unless she asked to become "a suspect" in the case.

Under Portuguese law a "suspect" has the right to remain silent - but if they are a witness every question has to be answered.

It is claimed Kate said it was "absurd" to be named a suspect but after a dinner break and a phone call to Gerry, she agreed.

"When she came back the climate had gone cold," the Diario De Noticias newspaper said. Another paper wrote of the second session of questioning: "She again got irritated with the questions."

One paper wrote: "Investigators told her accidents happen and when they do they are very lenient. There were more questions about the blood in the car and at the stage Kate stopped answering anything at all."

Re-interviewed on Friday, she again refused to answer questions about the blood.

Gerry was interviewed straight after Kate in an even "harder" interrogation.

Inspectors asked him if he had hidden the body. Maddy's father answered almost nothing and was described as "very angry".

Sources claim "the greatest suspicion has fallen upon Maddy's mother".

"Officers said her replies left a lot to be desired," it was claimed.

Overall the detectives concluded they they did not have a "great response" during the interviews because of "the couple's silence during 40 questions".

It was also reported two British sniffer dogs, one trained to react to the smell of a corpse and the other to traces of blood, showed "excitement" at the same spot in the apartment.