McCann's plea to police revealed

Kate McCann pleaded with Portuguese police to be kept informed about the hunt for her daughter, it has emerged.

A December 2007 letter from Mrs McCann, of Rothley, Leicestershire, to police said a lack of communication between officers and her family was "torture".

News of the letter comes as the family's investigators check reports that a girl calling herself "Maddy" was seen in the Netherlands in June 2007.

The information has been made public only with the release of police files.

Madeleine vanished, aged three, in May 2007 while on holiday in the Algarve.

Her mother's letter called for an end to "finger-pointing blame", and said her pain and anxiety were "indescribable".

Sifting through case files

The questions put to Kate McCann

Text of letter to police

Family spokesman Clarence Mitchell confirmed that Mrs McCann wrote to senior officer Paulo Rebelo but received no reply beyond a formal notification that her correspondence would be placed on file.

Mrs McCann wrote: "As her mother, the pain and anxiety I feel for her is indescribable and the feeling of helplessness overwhelming. The 'accusations' and media smearing, although upsetting, are very much secondary.

"I am appealing to you as a fellow human being to work with us (if possible include us) and to remember that we are Madeleine's parents and have needs...

"Lack of communication and a void of information, particularly as the parent of a missing child, is torture."

The McCanns, both 40, have accused detectives of withholding potentially crucial evidence from them after the release of the official documents.

"Madeleine called herself 'Madeleine', and that was very much the name in the family as well"
Spokesman Clarence Mitchell

According to one file, Anna Stam, 41, a shop assistant, said she spoke to a girl aged three or four in Amsterdam. She said she resembled Madeleine and said her name was "Maddy".

In reply to a question about her mother, the girl is said to have remarked: "They took me from my holiday."

A report was sent to Portugal on 18 June last year but it is not clear from the files what action was taken.

Mr Mitchell said it was "tragic" that this kind of evidence has only now been issued.

He said: "We need to know what happened with this. This is exactly the sort of primary information that we need to know if it was followed up properly by the police."

But he also told the BBC News channel: "Madeleine called herself 'Madeleine', and that was very much the name in the family as well, so that makes us wonder if this was indeed Madeleine."

The hair colour of the girl sighted in Amsterdam had been dark brown, different from Madeleine's blonde, Mr Mitchell added.

"That's not to say we are going to ignore any information based on one or two discrepancies - even one like that," he said.

"The lady concerned will be spoken to by the private investigators in due course and her information will be followed up.

"If it is Madeleine then of course that focuses everything. We are not saying it is. We need to know; we just don't know at this stage."

The release of thousands of Portuguese police documents also reveal that UK officers received intelligence suggesting Madeleine could have been snatched to order by a Belgian paedophile ring.

The intelligence suggested a "purchaser" in Belgium ordered the kidnap after being forwarded a photograph that had been taken of the girl.

But the files do not reveal the source of the intelligence.

The Portuguese police inquiry into the girl's disappearance was wound up last month.

The McCanns and a third British national, Robert Murat - who have always strongly denied having had any involvement in what happened to Madeleine - also had their status as formal suspects lifted.

Among the new files released was a prosecutor's report that said the investigation had uncovered "very little" conclusive about Madeleine's fate.

There were also CCTV images showing a small child said to resemble Madeleine at an Algarve petrol station the day after she disappeared that the McCanns had not seen before.

Several other reported sightings across Europe have been examined by local authorities or the investigators working for the McCanns in the past but all came to nothing.