It´s exactly the same here.
I´m a spanish ATCO, and we have always been blamed for giving priority to national (i dont think that even exists anymore) carriers. It doesn´t matter how many times we deny it, we are still today being blamed for doing so. guys, it really sounds ridiculous. Really.
I´ve been working at an Area unit for 11 years, and i have NEVER given priority to any traffic because of his nationality (again, guys, that is a very old-fashioned concept). Further more, as a supervisor and instructor, i have NEVER seen any of my colleagues give priority to anyone because of his nationality, colour of skin, sexual orientation or... pretty voice.
But actually this topic brings some excitement and enthusiasm to this forum, so go on.
Best regards.