Iraqi police say gunmen have killed 21 people in a raid on two Shi'ite homes northeast of Baghdad.
The attack in Diyala province raised concerns about more reprisal attacks between Iraq's Shi'ite and Sunni Arabs.
The top UN envoy to Iraq Ashraf Qazi warned that fighting could lead to a civil war, and he called for talks between Iraq's ethnic groups and the country's neighbors.
In Baghdad, officials said they would lift a curfew on Monday, imposed after bombings that killed more than 200 people in a Shi'ite district.
Suspected Shi'ite militiamen have killed 30 people in apparent reprisal attacks.
Elsewhere, the U.S. military says coalition forces destroyed an insurgent bomb-making factory today in raids which killed at least 22 insurgents and one civilian. And officials reported that a U.S. Marine died in combat in western Anbar province Friday.
Iraqi President Jalal Talabani postponed a trip today to Iran because the Baghdad airport has been closed since Thursday's attacks in Sadr City. A spokesman said he may leave Monday for the talks with Iranian President Mahmoud Ahmadinejad.