BAGHDAD—As Iraqis who fled their homes to escape sectarian violence are returning, many face high unemployment and poor access to electricity and water, according to a new report by the International Organization of Migration, a nongovernmental group operating in more than 100 countries.

In the worst cases, families return to discover that their homes are gone or have been significantly damaged. One-third of returnees interviewed by the group say they feel unsafe some of the time.

More than half a million families have left their homes since the war began in 2003, moving to other parts of Iraq or abroad, according to the group. The displacement accelerated after sectarian bloodshed escalated in 2006.

The researchers have identified 58,110 families who have returned, though some families have likely gone home without being counted by the organization's monitors. Most returned from other parts of the country rather than from abroad.

The returnees account for less than 10 percent of those displaced. Others said they wanted to return to their homes if conditions continued to improve.

The International Organization of Migration interviewed more than 4,000 families for the report.

The group's research showed that many of those who returned faced conditions as daunting as they had experienced in their temporary homes or shelters. Hardest hit were households headed by women, including those whose husbands were killed in the past six years. Among these families, which accounted for 12 percent of the families interviewed by the group, 70 percent of the women said they were unable to work, and 26 percent said they were able to work but could not find jobs.

In an example of what types of troubles returning families face, the police in Al Tahrir, near Baqouba, the provincial capital of Diyala, reported Friday that they had been called to the house of a family who had just returned after three years in Baghdad to find a vest loaded with 22 pounds of explosives and wires sticking out.

Neighbors told the police that members of the Islamic State of Iraq—an umbrella organization associated with al-Qaida in Mesopotamia, the Iraqi terrorist group believed to have some foreign leadership—had used the home as a safe house for suicide bombers during the family's absence.

The researchers found that about a third of the families they interviewed returned to find that their houses had been damaged or destroyed.

The report also found that returning families went home because of improved safety in their old neighborhoods, but also because of high rents and poor conditions in the areas to which they had fled. A small fraction, 5 percent of those interviewed, said they returned to take advantage of a one-time government grant of a million Iraqi dinars, roughly $840.

The returning families who spoke to researchers came from a variety of ethnic and religious groups: 50 percent were Shiite, 41 percent Sunni and 9 percent Christian.

One-third of the heads of household said they were unemployed. By comparison, a January study by the United Nations estimated that unemployment in Iraq was at 18 percent.