The couple -- a 39-year-old man and his 40-year-old wife -- were ordered detained by a court in Larissa, central Greece on charges of abducting the child, their lawyer Konstantinos Katsavos told AFP.
They face a sentence of between 10 and 20 years in prison if convicted.
Police found the blonde-haired, green-eyed girl named Maria in a Roma camp in the central town of Farsala on Wednesday, and the couple was arrested after DNA tests showed they were not related.
Though first described as a four-year old, the head of the Greek charity Smile of the Child, which has been caring for her, told local media dental checks suggest Maria is between five to six years old.
While police believe the girl may have been abducted at birth, the couple claims she was given up by her biological mother, who they say is Bulgarian, because she could not raise her.
"We're talking about a woman who could not raise this child and who gave it to the couple in 2009 through a third party shortly after her birth," a lawyer for the couple, Marietta Palavra, told AFP over the weekend.
"They did not buy the child," he said.
"We know the (girl's) parents are from Bulgaria," Marios Sainopoulos, a representative for the Roma community in Greece, told Skai TV today.
"The mother gave the child away because she could not raise it... The child was not kidnapped," he insisted.
Smile of the Child say they have been inundated with calls and emails in response to international media coverage of Maria's discovery.
"Until Sunday evening, we had received more than 8,000 calls and thousands of emails," charity spokesman Panagiotis Pardalis told AFP.
