(CNN) -- More people died violently in Iraq in April than in any other month in nearly five years, the United Nations said Thursday.
A total of 712 people died and 1,633 more sustained injuries "in acts of terrorism and acts of violence," the UN Assistance Mission for Iraq said.
Civilians made up most of the victims, 595 in total. 1,438 civilians were injured. Baghdad saw the most deaths with a total of 697 civilian fatalities.
April's total was the deadliest since June 2008, UNAMI said.
Since the overthrow of Saddam Hussein's government Sunni Arabs have been politically marginalized and Shiites, who represent a majority of Iraqis, have emerged with more power.
There have been protests for months by Sunni Arabs against the Shiite-led government and its prime minister, Nuri al-Maliki. The anger has escalated since a confrontation last week between police and protesters in Hawija.
The International Crisis Group last month said that the "failure to integrate Sunni Arabs into a genuinely representative political system in Baghdad risks turning Iraq's domestic crisis into a broader regional struggle."
"The most urgent task today is to tamp down the flames, and the burden for this lies above all with the government," the Belgium-based think tank said in a report.
"The country is at a crossroads," said Martin Kobler, U.N. special representative in Iraq.
Some Iraqi leaders and international powers fear that tensions between Sunnis and Shiites could escalate and bring a return of a full-blown sectarian war.