The Shiite prime minister says a return to sectarianism will result in a failed system.
Nearly all the bombings and deaths in the past week have targeted Shiite areas.
Iraq nearly slipped into civil war two years ago after attacks between Sunni extremists such as al-Qaida and Shiite militias and death squads.
The U.S. troop surge helped quell that conflict.
(Copyright 2009 by The Associated Press. All Rights Reserved.)