Greek police have released photos of a couple accused of abducting a blonde, blue-eyed-girl found living in a Roma camp, as the pair appeared in court.

Denying abduction, the couple told a closed court hearing in Larissa on Monday that her biological mother had willingly given her to them as a baby because she could not look after her.

The discovery of the girl, known as Maria, has riveted Greece and prompted thousands of calls with leads from across the world as authorities try to track down her real parents, after DNA tests showed she was not born to a Roma family.

The case has raised questions about whether children are being stolen to order and whether the couple were part of a wider child trafficking ring. It has deepened mistrust between the Roma community and the Greeks.

The couple were arrested after police raided a Roma camp in central Greece last week in search of drugs and weapons and found the girl, who did not resemble the family with whom she was living.

The couple deny they snatched the girl and say they took her under their care shortly after the mother gave birth.

"It was an adoption that was not exactly legal but took place with the mother's consent," Constantinos Katsavos, one of the lawyers representing the 39-year-old man, told reporters.

The couple were ordered to be held in custody pending trial after responding to charges of abduction and procuring false documents behind closed doors as more than a dozen policemen stood guard outside.

More than 5,000 people as far afield as Texas and Sweden have phoned the charity that is looking after Maria to offer clues or to search for their missing children.

Police believe that Maria, who has uttered just a few words in Greek and Roma dialect, is eastern or northern European.

Parallels have been drawn to the case of Madeleine McCann, who vanished while on holiday in Portugal in 2007, when she was three, and that of Ben Needham, who disappeared on the Greek island of Kos in 2001, when he was a toddler.

In the sunny, bustling square outside the court in Larissa, members of the Roma community gathered to show their support and said they were being unfairly stigmatised.

"They are completely innocent. These are all fairytales and we're going to prove it to society," Babis Dimitriou, the head of the local Roma community, told Reuters. "They accuse the Roma of everything – of stealing, of snatching kids. Do these things only happen among our race? This is a huge insult for us."

Police have found that the woman had two different identification documents and other papers suggested the couple had up to 14 children, but six were registered as having been born within less than 10 months.

"It's unfair," a Roma woman who gave her name as Kyriaki said outside the court after hearing of the decision to hold the couple in custody. "She raised this child since she was a baby."