Combine yeast, sugar and milk in large bowl; stir in 450g of the flour. Cover; stand in warm place 30 minutes or until foamy. Stir in oil, then remaining flour. Knead on floured surface about 10 minutes or until smooth and elastic. Place dough in large oiled bowl. Cover; stand in warm place until doubled in size.
Meanwhile, drain olives on kitchen paper.
Turn dough onto floured surface; knead in olives and oregano. Roll dough into 30cm x 35cm (11¾" x 13¾") oval; fold almost in half. Place on large greased baking tray; sift 2 tablespoons of plain flour over dough.
Bake, uncovered, in moderately hot oven 45 minutes or until cooked when tested; cool on wire rack.
Bread can be made a day ahead and warmed before serving. Store in airtight container.