Heat oil in large saucepan. Add the onion and cook for 5 minutes, stirring frequently until soft.
Add garlic, tomatoes, tomato paste, sugar, seasoning, stock, wine, and salt and pepper to taste and bring to a boil. Lower the heat, half cover the pan, and simmer for 10 minutes, sstirring occasionally.
Add the pasta and continue simmering, uncovered, for about 10 minutes, or until al dente, stirring occasionally to prevent the pasta from sticking together.
Add the clams and their juice to the soup and heat through for 3 to 4 minutes, ading more stock if required. Do not allow it to boil or the clams will become tough. Remove from the heat, stir in the chopped parsley and adjust the seasoning. Serve hot, sprinkled with pepper and parsley leaves.