That came about with the empowerment of the country's Shiite majority and the diminished clout of the Sunni minority which once held the power, reports The Washington Post. The situation has deteriorated since a Shiite shrine was destroyed on Feb. 22. The retaliatory killings that have gone on since then have raised concerns about an outbreak of civil war.
Shiites and Sunnis and other sects used to intermingle freely in the past but now green lines and red lines separate them in neighborhoods controlled by armed militias, says the report.
"Sectarian violence now has become the No. 1 problem in Iraq, more than the insurgency. Or on a par," says Ashraf Jehangir Qazi, the U.N. envoy to Iraq.
Separately, the BBC reports radical Shiite cleric Moqtada Sadr appealed for calm among his people in the wake of Sunday's bomb attacks in Baghdad which killed about 50 people.
Sadr also bitterly attacked U.S. Defense Secretary Donald Rumsfeld for saying Iraqi troops, and not U.S. forces, would intervene if a civil war broke out in Iraq.