Chop clams, reserving juice; set clams aside. Strain clam juice to remove bits of shell. Measure juice; add enough water to equal 1 1/2 cups liquid.
Combine clam juice mixture, clam-tomato juice cocktail, potatoes, bell peppers, scallions and black pepper in large saucepan; heat to a boil. Reduce heat; cover and simmer for about 15 minutes or until potatoes are just tender.
Stir in the undrained tomatoes and the chopped clams and heat through.
