The report from the U.N. Assistance Mission in Iraq describes a wave of lawlessness and crime, including assassinations, bombings, kidnappings, torture and intimidation.
Hundreds of teachers, judges, religious leaders and doctors have been targeted for death, and thousands of people have fled, the report said. Evidence suggests militants also have begun to target homosexuals, it said.
"While welcoming recent positive steps by the government to promote national reconciliation, the report raises alarm at the growing number of casualties among the civilian population killed or wounded during indiscriminate or targeted attacks by terrorists or insurgents," the U.N. said in a note accompanying the report.
According to the report, 2,669 civilians were killed in May and 3,149 were killed in June. Those numbers combined two counts: from the Ministry of Health, which records deaths reported by hospitals; and the Medico-Legal Institute in Baghdad, which tallies the unidentified bodies it receives.
The report charts a month-by-month increase in the number of civilians killed, from 710 in January to 1,129 in April. In the first six months of the year, it said 14,338 people had been killed.
The report's figures were higher than some other counts, but even the U.N. said many killings go unreported.
According to an Associated Press tally based on its daily reporting, at least 1,511 civilians were killed, in May and June, with at least an additional 289 police and security forces killed.
The AP tally said that from January through June 2006, at least 4,191 civilians were killed. The minimum number of police and security forces casualties in that period was at least 805 killed. The AP figures do not include insurgents.