The United Nations mission in Iraq said Tuesday that 979 people were killed there in September, most of them civilians caught up in the violence by Sunni insurgents, who appear determined to rekindle the tensions between Sunnis and Shiites that pushed the country to the brink of civil war in 2006-2007. The surge in violence followed a deadly crackdown by the Shiite-led government on a Sunni protest camp in northern Iraq in April. Since April, more than 5,000 people have been killed. The report said the worst-affected part was the capital, Baghdad, where 418 people were killed in September. It said 2,133 people were wounded last month.