BAGHDAD, Iraq — A U.N. report issued yesterday outlined an “ever deepening humanitarian crisis” in Iraq, with thousands of people driven from their homes each month, ongoing indiscriminate killings, and “routine torture” in Iraqi prisons.

Meanwhile, an American airstrike yesterday killed 15 civilians — nine women and six children — and 19 suspected insurgents, the military said. “We regret that civilians are hurt or killed while coalition forces search to rid Iraq of terrorism,” Major Brad Leighton, an American military spokesman, in a statement, said.

American troops targeting leaders of the Sunni insurgent group Al Qaeda in Iraq came under fire while approaching a building near Lake Thar Thar in western Anbar province, and aircraft fired on the site in response, the military said. The bombing also wounded six people, including one woman and three children. The assessment by the U.N. Assistance Mission to Iraq, which covered a three-month period ending June 30, found that civilians were suffering “devastating consequences” from violence across the country. It documented more than 100 civilians allegedly killed by American-led forces during air strikes or raids.

The report described Iraq in more dire terms than last month’s congressional testimony from top American military and embassy officials, which stressed improvements in the security situation.

“The killings are still taking place, the torture is still being reported, the due process issues are still unresolved,” a U.N. human rights officer in Baghdad, Ivana Vuco, said

The first draft of the U.N. report was completed in August, but the United Nations delayed releasing the final version for more than a month following a request by the American ambassador to Iraq, Ryan Crocker, according to a confidential account by a senior U.N. official. Mr. Crocker insisted that Iraq be given time to respond to the allegations, the account said; America then prepared critical assessments of the U.N. investigation that were included in the final report.

U.N. officials in Baghdad said the report was not intended to challenge the American military’s assertion that the ongoing troop escalation has helped reduce violence in much of Iraq. The reporting period ended before the time when the American military describes the sharpest drops in violence. The United Nations said it was not able to convince the Iraqi government to release civilian casualty figures, as it had in the past. Ms. Vuco said her organization was not trying to determine whether the situation in Iraq had improved or deteriorated. “As long as there are human rights violations, there are still concerns,” she said.

Among the most serious issues raised in the report is the treatment of detainees. The United Nations found that as of June, 44,325 detainees were in Iraqi or American custody, an increase of nearly 4,000 people since April, and that many of them remain in detention for months without having their cases reviewed or with limited access to legal counsel. The report also expressed concerns about overcrowding and poor hygiene in detention centers, particularly pre-trial holding cells run by the Ministry of Interior in Baghdad. The United Nations said it “remained gravely concerned at continuing reports of the widespread and routine torture or ill-treatment of detainees.”

“In addition to routine beatings with hosepipes, cables, and other implements, the methods cited included prolonged suspension from the limbs in contorted and painful positions for extended periods, sometimes resulting in dislocation of the joints; electric shocks to sensitive parts of the body; the breaking of limbs; forcing detainees to sit on sharp objects, causing serious injury and heightening the risk of infection, and severe burns to parts of the body through the application of heated implements,” the report found.

An Interior Ministry spokesman, Abdul Kareem Khalaf, said the ministry “totally rejects this report.” Mr. Khalaf said politicians, journalists, and human rights workers have visited ministry facilities and “they didn’t witness any kind of abuse.”

The U.N. report warned of an increased rate of violence against women, particularly “honor” killings, in the semi-autonomous Kurdish region in northern Iraq. In the first half of the year, regional government statistics counted 23 women killed by “blunt objects,” 195 by burning, and 37 by gunfire.