The Scots aunt of Madeleine McCann has claimed the anguish felt by the missing girl's parents over her disappearance was ­multiplied 100 times by a former Portuguese police chief's book about the case.

Trish Cameron, of Glasgow, said her brother Gerry McCann and his wife Kate had been vilified and demonised by Goncalo Amaral's unfounded allegations about the three-year-old's disappearance from Praia da Luz in the Algarve in 2007.

She said they had been left in "purgatory" by the disappearance of their daughter and the claims they were somehow involved.

Speaking at the libel trial of former police chief Goncalo Amaral in Lisbon, Mrs Cameron said his 2008 book and a linked TV documentary caused the family to be vilified and demonised.

Madeleine's twin siblings Sean and Amelie, now eight, told their parents that comments had been made by fellow pupils at their school, she added.

Mr Cameron told the court: "My brother and sister-in-law live in purgatory because they have no end and they are looking for the truth.

"They would like an end but there is no end because they don't know what's happened."

The McCanns say the former detective's claims in the book The Truth Of The Lie, including suggestions they hid their ­daughter's body after she died in an accident and faked an abduction, damaged the hunt for Madeleine and exacerbated the family's ordeal.

If successful in the legal action brought against Mr Amaral, his publisher, and the makers of the documentary, the family stands to gain around £1 million in damages.

Struggling to remain composed, Mrs Cameron said: "They were vilified in this book so their distress was multiplied 100 times.

"This pain was felt by all of their family because we still have a missing child and we knew that what is in [the book] is not true."

Mrs Cameron travelled to Lisbon with brother Gerry, who has applied to give evidence in the case.

Mr McCann still does not know whether he will be able to give evidence at the trial, and no decision was taken yesterday.

Other legal teams are thought to have until October 16 to make submissions on his application, ahead of the judge making her final decision.

Mr McCann said outside court: "Obviously it's disappointing, but we will just keep going."

Mrs Cameron told the court she thought she was the first person in the UK who Gerry called after Madeleine's disappearance in May 2007.

She spent three months in Portugal with Kate and Gerry, and later returned to continue to help the family. The nurse said the family drew up a rota to help Kate and Gerry when they first returned from Portugal, and had to put it back in place after the book was published in July 2008 as they struggled to cope with its effects.

"Kate was in a very low mood, she was not coping with daily things," she said. "She was doing solitary things, almost like torturing herself, out running long, long distances by herself.

"She was going to church and praying on a daily basis, and she was sleeping for a long time too.

"She wouldn't go out socially at all. She would not go to a shop. We had to help with practical things like the shopping and cooking and looking after the children."

She said the effects of the book were worse than when the McCanns were made "arguidos", or formal suspects, by the Portuguese police.

"It was much more conclusive and demonising them, dehumanising them, saying they did not care for their children, that they were responsible," she added.

Mrs Cameron said Madeleine's brother Sean had asked his father if he was famous after a fellow pupil asked him. Mr McCann replied, "No I'm not famous, it's because your sister is missing."

The case continues.