The 14-year-old, who was defenceless in her medical bed when the attack occurred last Friday night, suffered 225 wounds all over her body, including her face.
Police in the city of Roubaix, close to the Belgian border, were told last Sunday by hospital staff that the disabled girl had been admitted, the source told AFP.
An examination by a forensic pathologist determined that the injuries were caused by rats which swarmed her as she lay on her bed, according to a local newspaper.
The girl's father has filed a complaint against the landlord of the house and against the city, saying that he had repeatedly asked them to remove a pile of rubbish bins left in a nearby car park, the police source said.
A preliminary investigation has been opened to examine “housing conditions contrary to human dignity”, the prosecutor's office told AFP.
The town hall of Roubaix and the landlord were not immediately available for comment.