Violence killed around one thousand people in July, government and United Nations figures show, making it Iraq's deadliest month since 2008 when the country was emerging from a bloody sectarian conflict.
Bombings ripped through crowded cafes and mowed down worshippers at mosques last month, when militants also carried out brazen assaults on two prisons.
"The impact of violence on civilians remains disturbingly high," UN envoy Gyorgy Busztin said in a statement.
"We haven't seen such numbers in more than five years, when the blind rage of sectarian strife that inflicted such deep wounds upon this country was finally abating," he said.
Iraq was racked by a bloody Sunni-Shiite sectarian conflict that peaked in 2006-2007, when thousands of people were killed because of their religious affiliation or forced to abandon their homes under threat of death.
"I reiterate my urgent call on Iraq's political leaders to take immediate and decisive action to stop the senseless bloodshed, and to prevent these dark days from returning," Busztin said.
According to Iraqi government figures, 989 people were killed in July, including 778 civilians. More than 1,350 civilians were wounded in attacks, according to the figures compiled by the health, interior and defence ministries.
The figures make July the deadliest month since April 2008, when 1,428 people were killed.
The UN for its part put the toll for July at 1,057 people killed and 2,109 wounded.
According to the United Nations, more than twice as many civilians were killed in Iraq during the first six months of 2013 as were killed over the same period in Afghanistan.
In one of the month's deadliest single attacks, a suicide bomber detonated explosives in a cafe in the northern city of Kirkuk, killing 41 people.
Militants frequently targeted cafes, where Iraqis often gather after breaking their daily fast during the Muslim holy month of Ramadan, and also attacked mosques, where extended evening prayers are held during the month.
