Wash and dry oranges and lemons. Cut 2 oranges and 2 lemons into slices. Peel the zest of 1 lemon and 1 orange in a spiral with a peeler. Place the orange and lemon slices and the spirals in a punch bowl. Halve the lemon and orange and squeeze them. Pour in the juice and Campari and shortly before serving pour on iced Prosecco