As they face their fourth Christmas without Madeleine, the couple wrote on their website of their determination to find her.

They added: ‘We hope with all our hearts that wherever she is, she is safe and well and whoever may be with her is treating her with the love and respect she so deserves.’

Plea: Kate and Gerry McCann are begging their daughter's kidnappers to treat her with 'love and respect'

Madeleine was three when she went missing from a holiday apartment in the Portuguese resort of Praia da Luz in May 2007.

Madeleine's parents are facing their fourth Christmas without their daughter

Mrs McCann, 42, from Rothley, Leicestershire, said the ordeal had been made worse by WikiLeaks claims last week that British police had ‘developed evidence’ against them as they were investigated by Portuguese authorities.

She said: ‘The WikiLeaks “news” has led to the repetition of many unfounded allegations and smears.’

Mr and Mrs McCann, both 42, have won a series of libel payouts from newspapers over suggestions they were involved in their daughter’s disappearance.

But the leaked cable suggests British police were actively involved in helping to build a case against them.

The couple believe the decision to name them as arguidos jeopardised the hunt for their daughter, because it may have stopped potential witnesses from coming forward with information.

And it forced them to endure an agonising ten-month wait until Portuguese police admitted they had found no evidence against them, and shelved the case.

British police have always insisted they were responsible only for co-ordinating inquiries in Britain at the request of the Portuguese authorities.