Two people have been arrested and charged with the abduction of a child found at a Roma camp in central Greece.
A 40-year-old woman and 39-year-old man have been arrested as part of an investigation into whether the girl was a victim of trafficking.
DNA tests have shown the couple in the Roma camp with whom Maria was living were not her biological parents.
Greek police have asked Interpol to help them track down the real parents of a blonde girl with green eyes.
The four-year-old girl called Maria was spotted peeking out from under a blanket at a Roma settlement near the town of Farsala.
Police were carrying out a drug trafficking raid when they found the girl.
The girl speaks just a few words in Roma and Greek.
Police think she may be of northern or eastern European origin, possibly from Scandinavia or Bulgaria.
Police have sent Interpol a file with all the evidence they have on the girl.
Included are DNA samples, to seek a possible match with its records on missing children, a police official said.
They have also contacted international groups and charities that deal with lost or abducted children.
"Mystery - a blonde angel without an identity," top-selling daily Ta Nea wrote on its front page today.
Photos released by police of Maria staring blankly at the camera with muddy hands and scruffy pony tails have dominated the media.
Conflicting accounts of child's origins
During questioning, the couple gave at least five conflicting accounts of how the child ended up with them, including that she was found outside a supermarket, police said.
The woman had two different identification documents and other papers suggested the couple had up to 14 children.
Six were registered as having been born within less than 10 months.
The couple received €2,790 a month in child benefits, a police source said.
"This has never happened before - to have found the child and to be looking for the parents," said Natalie Karakouliafi of the Smile of the Child charity.
The charity is looking after the girl in response to an international appeal.
So far, it has received more than 5,000 calls since Friday from people looking for their missing children or offering clues.
The charity received reports that the girl was forced to beg for money in the streets.
The Smile of the Child charity director, Costas Giannopoulos,said she was in good health.
"She was frightened and cried herself to sleep. She is not looking for anyone and she is devoted to play," he told Reuters.
"It has shaken everyone and has helped bring to light a major problem - just how easy it is to traffic children".
Local police chief Vasilis Halastis told Greek TV: "We're always searching for lost children.
In this case we're searching for the opposite: the biological, natural parents. This is unprecedented."
Sister of missing Ben Needham seeks DNA test
The sister of a child who went missing in Greece more than 20 years ago says she wants her own DNA to be tested against that of Maria.
She is seeking this, on the off chance the girl is related to her missing brother.
Sheffield boy Ben Needham was just 21 months old when he went missing on Greek holiday island Kos in 1991.
His sister Leighanna Needham, 20, never met Ben but said the discovery of Maria in the gypsy camp was welcome news for her family's fight for answers.
"It's given us great hope," she told Sky News.
"Obviously, it's been a strong belief of myself and all my family that Ben was taken by gypsies for child trafficking or illegal adoptions and this case just shows that they can be found."
Ms Needham said the same technology could help find her long-lost brother.
"I think that would be a brilliant thing to get our DNA out there, even if it's not actually Ben but any siblings or any children maybe of Ben (that are found) then that could hopefully lead us to him," she said.