The Shiite-dominated parliament Wednesday passed a law allowing the formation of federal regions in Iraq, despite opposition from Sunni lawmakers and some Shiites who say it will dismember the country and fuel sectarian violence.

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The federalism law sets up a system for allowing provinces to join together into autonomous regions that would hold considerable self-rule powers, a right given to them under the constitution adopted last year in a national referendum.

Some Shiites want to create an autonomous zone in their heartland in the south, much like the self-ruling Kurdish region in northern Iraq.

But Sunni Arabs deeply oppose the federalism measures, fearing it will divide Iraq into sectarian mini-states, giving Shiite and Kurds control over oil riches in the south and north, and leaving Sunnis in an impoverished central zone without resources. Some Shiite parties - including the faction of radical Shiite cleric Muqtada al-Sadr - also oppose the measures for nationalist reasons.