A woman is reported to have flown from Istanbul to Paris with a four-year-old girl hidden inside her hand luggage.
The child, travelling without a ticket, was discovered on board the Air France flight on Monday night.
An airport source told AFP news agency that the woman was a resident of France who was in the process of adopting the child, from Haiti.
The airline notified the French authorities but prosecutors decided not to press charges.
The woman entered the transit zone in Istanbul but was prevented from boarding her flight with the child, the source told AFP.
She then bought a new flight ticket and hid the child in a bag.
Once on board, she placed the child at her feet under a blanket, but the girl needed to go to the toilet and was noticed by other passengers, the source said.
The woman and the girl were held at Charles de Gaulle airport in Paris while authorities investigate the case.