"Human rights violations, particularly against the right to life and personal integrity, [have] continued to occur at an alarming daily rate in Iraq," the report, released on Wednesday, said.
Bodies found in the Baghdad morgue "often bear signs of severe torture including acid-induced injuries and burns caused by chemical substances, missing skin, broken bones - back, hands and legs, missing eyes, missing teeth and wounds caused by power drills or nails," the report said.
The monthly report said that terrorist attacks, the growth of militias, the emergence of organized crime had resulted in the large-scale and indiscriminate killing of civilians.
Every month the Iraqi police continue to find hundreds of bodies bearing signs of "severe torture and execution style killing" the report said.
Displacement of civilians
The UNAMI report also found that the displacement of civilian population "has also continued to grow" and now affects all governorates in the country.
The report also said that torture is common in official detention centers and that the bodies of many Iraqis executed extra-judicially executed by death squads, insurgents and militias bear also signs of severe torture.
These widespread human-rights violations were threatening the cohesion of the Iraqi state, the report said.
"The inability of state institutions to bring perpetrators of human rights violations to justice and to provide adequate protection to ordinary citizen ... risk polarizing Iraqi society to a previously unknown degree and result in a self-reinforcing pattern of sectarian confrontation," it said.
Honour crimes increase
The document also reported an increasing number of "honour crimes" against women.
"In their fight against generalized violence, central, regional and local authorities should provide greater protection to women from crimes committed within the family, including all types of violence against women and girls on the grounds of honour," said the report.
Many Muslim societies condone the killing of women whose behaviour is seen as compromising the honour of their family or husbands.
UNAMI said that Iraq's failure to bring criminals to justice risked making Iraq even more lawless.
"A growing perception of impunity for current and past crimes committed risks further eroding the rule of law," it said.
In its latest human rights report for the months of July and August, UNAMI said that 3,009 Iraqi civilians died violently in August.
This was a slight decrease from the 3,590 civilians reported killed in July, the report said.