Heat oil in a large frypan over medium-high heat. Add green capsicum, onion and garlic and cook until pepper is soft, about 5 minutes. Mix in the white pepper, cinnamon, lime juice, olives and chillis; cook for 2 more minutes to blend the flavours. Stir in the tomatoes and cook until thickened, about 10 minutes.
Preheat the oven to 180 degrees C. Place the snapper fillets into a lightly greased 20x30cm baking dish. Pour the vegetables over the fillets and bake for 10 to 15 minutes in the preheated oven, or until fish flakes easily with a fork. Stir in the capers just before serving.