April was Iraq's bloodiest month for almost five years, with 712 people killed in bomb attacks and other violence, the United Nations Iraq mission said on Thursday.
Iraq has grown more volatile as the civil war in neighboring Syria strains fragile relations between Sunni and Shia Muslims. Tensions are at their highest since US troops pulled out in December 2011.
The number of attacks increased sharply after security forces raided a Sunni protest camp near Kirkuk last week, triggering clashes that quickly spread to other Sunni areas including the western province of Anbar, which borders Syria and Jordan.
"The month of April was the deadliest since June 2008. A total of 712 people were killed and another 1,633 were wounded in acts of terrorism and acts of violence," a UN statement read.
The number of civilians killed last month was 434 while the toll of security forces personnel was 278.
Iraqi authorities published a monthly death toll for April on Wednesday which was much lower than the UN figure. The interior ministry said 245 people, including 84 members of the security forces, were killed.
Iraqi authorities often report lower estimates for the number of victims of attacks for unclear reasons, but April's toll is still the highest since the beginning of the year.
Violence is still well below its height in 2006-07, but al-Qaeda's Iraqi affiliate and other Sunni Muslim insurgents are launching attacks on a daily basis to undermine the power of the Shia-led government and provoke wider confrontation.
Iraqi politics are deeply divided along sectarian lines, with Maliki's government mired in crisis over how to share power among Shia Muslims, the largest group, Sunnis and ethnic Kurds who run their own autonomous region in the north.