Madeleine McCann's parents could face years in Europe's courts fighting claims they invented their daughter's abduction to cover up her death.

Goncalo Amaral, the former Portuguese detective who initially led the investigation into their daughter's disappearance, has vowed to keep appealing if he loses a libel trial over a book in which he claims Madeleine is dead.

Amaral said his attempt to overturn the injunction on allegations the McCanns were involved in their daughter's disappearance was about "fundamental rights" and pledged to keep fighting all the way to the European court of human rights.

Outside the hearing in Lisbon, where the couple have been seeking to ban the book, Kate McCann admitted that listening to allegations they faked Madeleine's abduction was difficult but said nothing could be as bad as losing her child.

"If I'm honest, our daughter's been taken and nothing's ever going to be as bad as that. It's still been difficult, it's been emotive, because I know what's in the case files, I know what the conclusions are. So it's difficult to hear something that's incorrect and inaccurate. At the bottom of all this is a little girl and I think it's important that we don't forget that."

She said she did not regret pursuing the case. "I am pleased that we took the action and think that it will benefit Madeleine," she said. Asked if she believed they would win their case against Amaral, she said: "I am confident, yes."

Isabel Duarte, the McCanns' lawyer, accused Amaral of trying to put the couple on trial. The court has heard from a series of senior Portuguese officials who have claimed the McCanns were responsible for their daughter's death.

"They are trying to judge in a civil court what they could not judge in a criminal court," she said. "I am sorry my clients had to be submitted to this pain and this distress. This is awful, but we knew that Pandora's box was open."

Kate McCann was today accompanied to the third day of the trial by Fiona Payne, one of the "tapas seven" group of friends who were on holiday with the McCanns in the Algarve resort of Praia da Luz when their daughter disappeared. Gerry McCann, who had been in court on Tuesday and yesterday, flew back to Britain last night to return to work.

The court today heard evidence from producers of a TV documentary based on Amaral's book.

The case has been adjourned until 10 February when the judge will hear from two witnesses not available this week. A ruling is expected by the end of February, however the case is just one step in a lengthy legal battle.

The McCanns are seeking €1.2m (£1.08m) in compensation for defamation in separate proceedings against Amaral but no date has been set for a trial.