The possible sighting of the missing girl was reported to Portuguese officers in June last year. But it has only now been made public with the release of previously secret police files.
The McCanns accused detectives of withholding potentially crucial evidence from them after the newly-released official documents revealed a series of leads they knew nothing about.
The Dutch sighting was perhaps the most promising of the lines of inquiry that have emerged.
Shop assistant Anna Stam, 41, said she spoke to a little girl aged three or four in Amsterdam who said her name was "Maddy" and replied to a question about her mother: "They took me from my holiday."
The girl entered Ms Stam's party shop in early May last year with a man and a woman and two other children, according to a witness statement to Dutch police.
The man - who "did not look like a nice person" - appeared to be speaking Portuguese but the woman spoke in English and told Ms Stam they had a small circus in France. Ms Stam was at the back of the shop when the young girl approached her and asked in unaccented English: "Do you know where my mummy is?"
On being told that her mother was a little further back in the store, the child replied, "She is not my mummy," and added: "She is a stranger, she took me from my mummy."
The Dutchwoman said she thought the girl looked "very much like" Madeleine apart from the colour of her hair.
The report was sent to the Portuguese authorities on June 18 last year but it is not clear what action was taken. (Sky News Wednesday 6th August 2008)
