A girl born to an unwittingly incestuous couple has had her full parentage acknowledged by a French court, in apparent contravention of the country's civil code, it has been reported.

Eight-year-old Océane was born to half-siblings Rose-Marie and Hervé in 2009. The pair, who have the same mother, were raised apart and did not know each other until they met and fell in love in 2006, according to local media.

They did not learn of their shared parentage until they applied for a birth certificate for their daughter, according to The Local.

Rose-Marie raised the girl from birth, and the court of appeal in Caen ruled earlier this year that annulling her legal parentage of Océane would have "damaging consequences" for the youngster, overturning a previous judgement.

Lawyer Catherine Besson, representing Hervé, called it a "happy decision", Le Parisien reported. The father had argued that if one parental link had to be annulled it should be his, as he had not raised his daughter, she said.

The site said that ordinarily, children of incest can have official filiation registered only for one parent. Whether authorities will appeal the latest ruling was not known, it reported.