It's well documented throughout history that The Maltese used to have Black slaves, though that isn't really the present problem. It's sort of ingrained in them, until the 1990's it was normal for bars and restaurants to have signs saying: No Arabs - No Blacks - No Dogs.
Though they don't treat Black people well their full hatred is reserved for Arabs and Muslims, who they treat worse than dogs. The Catholic Church probably has a good deal of responsibility for that.