Gerry and Kate McCann are taking legal action against Goncalo Amaral over his "absurd and deeply hurtful claims" that they were involved in concealing the body of their daughter, who disappeared from their holiday apartment two years ago.
 

But on Sunday the retired police officer, who led the Madeleine investigation for five months before being removed from the case, pledged to retaliate.

"My lawyers are working on the case and we will take the McCann couple to court and perhaps other people for defamation, slanderous denunciations and false statements," he said.
 

"We will see who has spoken the truth in this case."

Mr Amaral, 49, published a book called The Truth of the Lie last year in which he alleged that the McCanns covered up Madeleine's death, even though they have been formally cleared by the Portuguese authorities. He has repeated his claims in a television documentary and a recent newspaper article.

In a statement announcing their legal action, the McCanns said the former officer had "brought indescribable devastation and suffering to our lives" and was hindering the hunt for Madeleine.
 

"We can no longer stand back and watch as Mr Amaral tries to convince the entire world that Madeleine is dead," they said.
 

The McCanns, from Rothley in Leicestershire, have attempted to kick-start the search for their daughter by releasing a photo of how she may look today, and appealing for more information in an appearance on the Oprah Winfrey show.

The couple had their status as "arguidos" removed in July 2008, 10 months after being named formal suspects. Portugal's chief prosecutor said the police had found no evidence linking the McCanns, or fellow suspect Robert Murat, to Madeleine's abduction.
 

Mr Amaral was taken off the investigation after claiming that the British police were too responsive to the McCanns' demands.