A leading Portuguese bishop has told the parents of Madeleine McCann that he is willing to negotiate their daughter's release.

The Bishop of the Algarve, Manuel Neto Guintas, today offered to act as an intermediary between the McCanns and their daughter's abductor if needed.

Bishop Guintas appealed to the "heart and mind" of the abductor to bring the four-year-old back. His appeal came as the McCanns marked yet another painful milestone in their daughter's disappearance: it has been three weeks exactly since the four-year-old was stolen from them as she lay sleeping.

Bishop Guintas said: "Madeleine must be reunited with her parents as soon as possible. They are going through terrible pain and I am willing to help in whatever way I can.

Gone but not forgotten: The McCanns praying for their own miracle - the return of their beloved daughter Madeleine

"If it comes to the point that a go-between is needed to negotiate her release, then I am very happy to do that."

The bishop told a Portuguese religious newspaper that he had written to the McCanns to offer his support "in whatever form they required".

The bishop, who is well known for his outspoken opinions and frequent media appearances.

Yesterday the McCanns visited the famous Fatima shrine as they continued their desperate prayers for their daughter's safety.

Madeleine was snatched three weeks ago from her parents' apartment in Praia da Luz, a resort just outside the town of Lagos on the Algarve.

When her mother Kate visited Fatima, she held her missing daughter's toy and a wellwisher's rose. All she had in her heart was hope.

But as she lit the candle for Madeleine at one of the holiest sites in Europe, Kate McCann was keeping that hope alive in the only way she could.

She stood side by side with her husband Gerry at the Shrine of Fatima and prayed for a miracle. Gently, she placed a kiss on the candle and left it among hundreds of others at the Portuguese basilica.

Then she travelled back to Praia da Luz to continue her agonising wait.

The couple's brief pilgrimage to Fatima yesterday came on Day 20 of the search for Madeleine, another 24 hours without the news for which they have been waiting.

Determined: Gerry McCann and wife Kate in Portugal

 . They have made a pilgrimage to the famous Portuguese shrine at Fatima to pray for a miracle

The McCanns joined thousands of other pilgrims at the shrine in central Portugal, renowned as the site where the Virgin Mary is said to have appeared 90 years ago, and revered by fellow Roman Catholics across the world.

Mary is said to have shared three visions here with three shepherd children - a vision of hell; a prediction of the Russian Revolution, the spread of Communism and the Second World War; and the attempted assassination of a pope, taken to be a reference to the shooting of Pope John Paul II in 1981.

No one had to ask the McCanns what miracle vision they had in mind.

The couple arrived after a four-hour drive from Praia da Luz and were escorted into the basilica square. Their faces are familiar in Portugal and scenes that unfolded around them were almost Biblical.

In the spotlight: The McCanns prepare to face the world

Crowds parted to let them pass. Then a multitude of well-wishers, TV cameras and applauding pilgrims pursued them around the square before they disappeared to a private chapel to pray alone.

After nearly an hour they emerged to light their candle and place it with the others, along with four more that various pilgrims had thrust into their hands.

Manuel Ines, who had travelled to Fatima specifically to meet the McCanns, held his 17-month-old great grandson aloft and invited them to kiss him. Young Daniel duly received a kiss from the couple before they were swept off to join a public Mass.

Here, in the Chapel of Apparitions, they sat near a framed photograph of Madeleine, left several days ago by an unknown pilgrim.

 

Gerry and Kate McCann at church again

Monsenhor Luciano Guerra, Rector of the Shrine, offered prayers for their daughter - and added a message in Portuguese for families everywhere: "Let us pray to the Lord for all the parents who do not have time to play with their children. Let us summon the three little shepherds, for all the children that are away from their homes, especially little Madeleine, so that Our Lady can keep these children in her care."

He prayed for help for those investigating Madeleine's disappearance, "so that this tragedy can come to an end". And in a message to any abductor he added: "Let us pray so that these vultures can be enlightened and converted."

Fatima is one of the places the McCanns have long wanted to visit, and they were originally planning to fit in a trip during their holiday. How they must have yearned to have been able to enjoy it as an anonymous family of five. This was the first time since Madeleine, four, vanished that the couple have left Praia da Luz together, except to give statements to police.

A family spokesman told us: "Kate is anxious to get back as soon as possible because she feels a strong connection to Madeleine there and a connection to the search.

"It's very hard for her to leave. But they were very pleased to come here. Their faith is very important to them and this was a profoundly moving and important spiritual visit for them at this time.

"The fact that so many people are praying for them and for Madeleine is enormously uplifting. They take strength from every single prayer."

•Police have taken fresh statements from suspect Robert Murat's girlfriend. Michaela Walczuch and her husband Luis Antonio - with whom she still lives in a nearby town - were taken for questioning at police headquarters in Portimao.

Police sources said they were being treated as witnesses.

Four-year-old Madeleine has been missing for three weeks exactly today