Authorities in Croatia are looking for the parents of a mysterious girl found in a park a month ago - but no one knows her name, her age, or even what language she speaks.

All that's known about the girl, who they call Nina, is that she appears to be around three years old, has brown hair and brown eyes and was found in a park in Velika Gorica, Croatia.

Authorities believe she may have lost her family as they fled to Europe from Syria, Sky News reports.

They admit they have no idea where she comes from but are hoping media attention will help reunite her with her family.

Croatia's Family Minister Milanka Opacic invited journalists and film crews to meet Nina at Zagreb's Child Care Centre, to help find "anyone anywhere" who recognises her.

"So far we have no new information, we still can't figure out the language and country of origin of the child," she said.

"Today we decided to ask you, the media, to help find out her identity.

"The media can place her face in foreign media, due to your international co-operation.

"It's very important to us that anyone anywhere recognises her, so we can contact any members of her family."