A Greek charity said yesterday that it was pursuing at least 10 "promising leads" – many from parents whose children had gone missing – following a worldwide appeal to help identify a blonde, blue-eyed girl found living in a Roma camp in the country.

Less than two days after launching the international campaign, the philanthropic organisation Smile of the Child announced that it had been bombarded with more than 10,000 calls and emails from around the world.

"Through our hotline we've been contacted by thousands of people in the US, Canada, Australia, Scandinavia, South Africa and the UK," Panaghiotis Partalis, the charity's international communications officer, told the Guardian.

"A lot of emails have come through from families whose own children went missing years ago. Based on pictures that we have also received, there are around 10 cases of children who bear a resemblance to the little girl and we are following them up to see if there is any link."

The girl, who is thought to be about four years old and answers to the name Maria, was discovered last Wednesday when Greek police raided a Roma settlement near Farsala in Larissa, 170 miles north of Athens, in search of weapons and drugs.

Officers were said to be taken aback when the pale-skinned child appeared in the home of a couple with 13 other offspring who were all dark-skinned. Unable to communicate in Greek, the girl could barely talk. What little she did say was conducted in the Roma dialect.

In a bid to unearth her identity, Partalis said the charity was also looking for specialists, including an anthropologist, who might be able to determine the child's origins and age.

"There is still mystery surrounding her age," he said. "We are looking for experts who can examine her teeth and other features to find out exactly how old she is and what her origin may be."

The charity has also compiled a "profile" of pictures of lookalike children. "We've put together a montage with Maria at the centre that we have passed to the police," he said. "There seems to be a lot of hope in the Swedish press that she is Scandinavian."

The girl is expected to be released from hospital on Monday, the same day the couple found raising her are due to appear in court on charges of abducting a minor. Police said it was likely they would be imprisoned pending trial. "The father already has a criminal record," said one officer in Thessaly, the region where the child was found.

DNA tests have proved conclusively that the little girl is not related to the couple – a 40-year-old woman and 39-year-old man.

Although the suspects have vehemently denied accusations of child smuggling, they have given a range of conflicting stories, telling investigators at first that the girl was found in a blanket at birth, before insisting her biological father was Canadian. Suspicions were further raised when the mother was discovered to have two identities and to have claimed to have given birth to six of her children in the same year. Costas Giannopoulos, who founded Smile of the Child after the death of his own son, said the discovery of the girl had not only shone a light on child trafficking in Greece, but revealed the parlous state of birth registrations with municipal authorities in the crisis-hit nation.

"There is a huge gap that allows anyone to claim a child as their own," he said.

On Friday, the parents of Madeleine McCann, the toddler who went missing in Portugal in 2007, said the case was a sign that children who had disappeared could still be found.

Authorities hope that the discovery of the girl will also help crack the mystery of Ben Needham, the Sheffield boy who went missing at the age of 21 months on the Aegean island of Kos 22 years ago. Ben's mother, Kerry Needham, told ITV: "My family and I are extremely delighted at the news that a four-year-old girl has been found in a gypsy camp in Larissa, Greece. We have always believed that Ben's abduction was gypsy-related and have a long ongoing inquiry in Larissa. We hope that the investigation into Ben's disappearance will now be looked at again."