'DNA blunder turned Kate McCann into suspect

The claim comes as Portugal's attorney general formally cleared Kate and Gerry of any involvement in the disappearance of Madeleine in May last year.

According to the Portuguese, the British Forensic Science Service told them that DNA evidence found in the couple's hire car a month after the girl went missing was categorically Madeleine's.

This led to the McCanns being questioned and made suspects. But one month later the forensic service said it could not be sure whether the DNA belonged to Madeleine, her mother or to her sister Amelie, the report says. Madeleine's DNA was also allegedly found on the window sill of their Algarve holiday flat and in the car park. The McCanns always insisted that such DNA could have come from rubbish, including nappies, they cleared from the flat when they moved out.

Another error highlighted in the report was that when British "cadaver dogs" apparently caught the scent of death in the flat, Portuguese detectives did not take into account that GP Mrs McCann had come into contact with six patients who died before she went on holiday.

There is also strong condemnation of the police for paying too much attention to the media during the massive hunt for the girl. Evidence given by the seven friends the McCanns were dining with when Madeleine disappeared is criticised as they are accused of contradicting each other.

The report also talks about a key witness who contacted the police three weeks after the disappearance saying he saw Mr McCann carrying Madeleine away from the flat on the night she disappeared but later retracted his statement.

The report says there is a strong belief by British and Portuguese police that Madeleine is dead.

Kate and Gerry, both 40, who believe their daughter was abducted and is still alive, were aiming to spend today as routinely as possible. Mr McCann, a consultant cardiologist, went to work at a Leicester hospital while his wife took their three-year-old twins to nursery school near their home in Rothley. She was then said to be seeing friends.

Madeleine was six days short of her fourth birthday when she vanished from her family's holiday flat in the Ocean Club complex at the Praia da Luz resort. The third suspect, Algarve property consultant Robert Murat, 34, also had his "arguido" status lifted.

The claim about the DNA evidence is likely to cause the Forensic Science Service embarrassment. Last week representatives of the service went out to Portugal with Leicestershire police to try to prevent the information being made public. Mark Williams-Thomas, a former police officer and a child protection expert, who has knowledge of the report, which dedicates 50 pages to the DNA evidence, said it was "damning".

"The FSS was out in Portugal on a damage limitation exercise," he said. "They will lose credibility over this."

It is understood that even if the case is shelved, the files will be periodically reviewed and could be reopened if new evidence emerges.

The policeman in charge of the original investigation was revealed to be publishing a "tell-all" book. Gonçalo Amaral, who was sacked as head of the inquiry in October, took early retirement last month.

Mr Amaral, 48, authorised the decision to name the McCanns as official suspects and his book, called True Lies, will be released in Portugal this week.

He told BBC News today: "The evidence that we had gathered by the time that I left the case, pointed to the girl being dead - and having died inside the apartment. I don't know what happened next. I can't say. We'll have to wait for the case files to be made public."

Mr Amaral said the decision to make the McCanns suspects was taken by a number of officials and did not amount to a "persecution".

Mr Mitchell added: "It's a great shame that Mr Amaral apparently feels the need to make money out of Madeleine's disappearance.

"We hope that any profits he makes from this book will go to the fund to find their daughter but we are not optimistic.

"Until the judicial secrecy is lifted, he is covered by those laws in the same way as everybody else associated with the case is, and as a result Kate and Gerry's libel lawyers will read that book with great interest."