A libel trial against a policeman in Portugal who claimed missing British girl Madeleine McCann was dead and that her parents could have hidden the corpse opened yesterday but was immediately postponed.

The case in Lisbon against former Algarve police officer Goncalo Amaral, who led the early stage of the investigation into Madeleine's disappearance, was adjourned until January 12 due to the absence of his lawyer.

Madeleine's parents, Kate and Gerry McCann, attended the opening of the case yesterday, which they brought against Amaral for suggesting their daughter was dead and that they were somehow involved in the disappearance.

He wrote a book, The Truth Of The Lie, about Madeleine's disappearance which contained these allegations.

A Portuguese court issued an injunction in September banning sales of the book and prohibiting Amaral from repeating his claims in the media.

"Freedom of speech should not include distortion of the truth, lies, fabrication and slander," said Kate McCann, yesterday.

She added the couple were not disappointed about the trial delay as the injunction was still in force.

Gerry McCann added: "The key thing here is we're here to fight for our daughter, and if anyone steps over the lines, then they should be prepared to defend what they say in court."

Madeleine, who would now be six years old, went missing from a holiday apartment in the Algarve resort of Praia da Luz on May 3, 2007, as her parents and their friends were eating at a nearby restaurant.

Mr Amaral was in charge of the investigation into her disappearance when her parents were made official suspects in September 2007.

He was removed from the case a month later, and Portugese prosecutors announced in July 2008 that the McCanns were no longer suspects.

Despite huge publicity worldwide and investigations by Portuguese and British police, Madeleine has not been found.

Portuguese police are no longer investigating the case, but other investigators acting on the couple's behalf are still looking for the missing girl and appealing to the public for information.