Police should shelve their investigation into Madeleine McCann's disappearance, Portugal's attorney-general appeared to say today.

His country's detectives have nothing to be ashamed of if they can't trace her because it is statistically likely she will never be found, said Fernando Jose Pinto Monteiro.

Speaking as the McCanns and their family marked the year anniversary of the toddler's disappearance with a church ceremony in Praia da Luz, he said: "If the investigation results in failure, it is nothing which should shame the police.

Balloons are released at a heartbreaking anniversary memorial for missing Madeleine McCann

"These kinds of crimes are extremely difficult to investigate. There are one million missing children per year throughout the world, and not even 20 per cent are found."

His comments follow criticism of Portuguese detectives by Madeleine's parents Kate and Gerry McCann for being more interested in investigating them than the four-year-old's disappearance.

The couple, who believe Madeleine is alive, told in an ITV documentary last week of their shock and anger at being named as arguidos, or official suspects.

Mrs McCann, 40, said: "As soon as I realised the story or theory was that Madeleine was dead and that we'd been involved somehow, it just hit home. They haven't been looking for Madeleine."

The church in Praia da Luz which has been such a source of support for the McCanns, (below) a collage of articles and pictures on Madeleine

But Mr Monteiro also insisted to Portugal's Jornal de Noticias newspaper that the police had done what any other police force would do to solve the mystery of what happened to the little girl, adding:

"It may be that we find out yet - let's wait until the end (of the inquiry)."

The couple vowed to find Madeleine themselves last week as they launched a fresh appeal to anyone with any information to make contact with their investigators via a new hotline.

They have been kept in the dark about the thousands of clues that have flooded into police since Madeleine, then three, vanished in Praia da Luz on May 3 last year.

strong>

Scroll down for more

Emotional: Kate and Gerry McCann leave the church service, where they both wept

Mr McCann said: "We've got little bits of the jigsaw and we've got huge gaps. People [Portuguese police] have had a fair crack. As parents we just want to make sure everything possible has been done."

Mrs McCann added: "You get to the point where you think we will have to find out for ourselves."

Yesterday Kate McCann begged friends and family to keep Madeleine in their prayers at a church service to remember her daughter a year on from her disappearance.

In a tearful and unplanned plea from the pulpit, Kate told them: "Pray like mad. Please stay with us, stay with Madeleine...keep praying."

Scroll down for more

Keep praying: a poster advertises the prayer service for Madeleine

Appearing fragile after a week-long media blitz to publicise the hunt for her child, Kate had held her head down for much of the service at St Mary and St John, in Rothley, Leicestershire.

Gently sobbing at times, she appeared a broken figure, one year on to the day her then three-year-old went missing from Praia da Luz, Portugal.

Next to her in the front pew of the packed church sat her husband Gerry, holding her hand and staring ahead.

At the end of 40 minutes of prayer, Kate, wearing blue jeans, a floral blouse and a beige jacket, rose unexpectedly to thank friends and say how much their three-year-old twins Sean and Amelie missed their sister.

She was barely audible, and struggled to hold back tears, as she said: "I have spoken quite a lot this week so I will keep it short.

"It is just to say a huge thank-you really for coming to remember, for your support.

"We have been quite strong but couldn't have got through without you.

"You know how much she means to us, and to Sean and Amelie.

"We know you have been praying and we ask you to keep going."

As Kate, 40, returned to her pew, the 200-strong congregation applauded and friends rushed to console her as she fell weeping into her husband's arms.

Also in church were David and Fiona Payne, and Rachel and Dr Matthew Oldfield, four of the 'Tapas Seven' friends who were dining with the McCanns when Madeleine vanished.

Gerry, 39, was hugged by friends and wept at the end of the service ? which included a prayer written by the Archbishop of York, Dr John Sentamu.

Kate's aunt, Janet Kennedy, said: "How Kate mustered the courage to speak, I don't know. But it was very inspiring."

Kate and Gerry only finally decided to attend the service yesterday after a relentless tour of TV studios.

A friend revealed Gerry had to be persuaded to not volunteer to be on call over the weekend at Glenfield hospital, in Leicester, where he is a cardiologist.

Kate has vowed not to return to work as a GP until Madeleine is home.

The friend said: "They are trying to get their lives back to normality.

"But Gerry could see in the end that he couldn't be on call on this weekend."

The couple's spokesman, Clarence Mitchell, admitted they were finding the anniversary more painful than they had anticipated.

He said: "It is an intensely private day, very difficult. In some ways being at home is the best place but in other ways it is the worst."

On his blog, Gerry wrote: "It has been the longest year of our lives, yet it does not seem like a year."

In a Portuguese newspaper Gerry admitted he has struggled with guilt over enjoying time with the twins while Madeleine is missing.

Meanwhile, Gerry's brother John, 48, arrived in Praia da Luz before a candlelit mass.

He said: "We are here to thank the people of Portugal who have supported Gerry and Kate. We really do feel we can get Madeleine back."

Scroll down for more...

Heartbreaking anniversary: Madeleine has been missing for exactly a year

Last night, it was revealed the McCanns' financial backer, tycoon Brian Kennedy, had met Robert Murat, the first suspect in the case.

The meeting took place at Mr Murat's aunt's house in the Algarve last year.

Mr Murat's lawyer, Francisco Pagarete, said: 'We had a very pleasant dinner with Mr Kennedy.

"He came here to give his support to Robert and to say he doesn't believe Robert was involved in this story in any way.

"And he asked if Robert could help the investigation for the finding of Madeleine."

It is understood the meeting in November was also attended by Mr Kennedy's lawyer, Edward Smethurst, who is co-ordinating the McCanns' legal affairs.