The French deny it? The Mayor of Paris hardly represents all French. Besides I found links to French TV documentaries on the subject, aired by networks TF-1 and channel 3.
I assume that you are talking about the no-go zones? These zones have been talked about for years but now the locals deny them - not really sure what to make of this.
I’m sure that there are areas that the police will not go willingly but that they deny it is telling...