NEW ORLEANS (AP) — Children who lived in emergency trailer parks or federally subsidized hotels for long periods after Hurricane Katrina are far more likely to have serious emotional problems than other children, a new study finds.

About 500,000 people, including more than 160,000 children, weren’t able to return to their homes for at least three months after the storm hit on Aug. 29, 2005.

At least 20,000 of those children still have serious emotional disorders or behavior problems, or don’t have a permanent home — they’re either in transient housing or can’t be guaranteed a place to live for more than a year, according to the report being released Monday.

‘‘Five years after Katrina, there are still tens of thousands of children and their families who are still living in limbo with a significant toll on their psychological well-being,’’ said Irwin Redlener, head of the two organizations releasing the report: the Children’s Health Fund and Columbia University’s National Center for Disaster Preparedness.

Without significant government help, Redlener said, these children are likely to have even greater problems as adults.

Psychologist Joy Osofsky of the LSU Health Sciences Center agreed, but said it was also important to note that children in general are much more resilient than those from the extremely poor families Redlener is studying.

Osofsky, who has been working with children at St. Bernard, Plaquemines and Orleans parish schools since the storm, said Redlener’s study shows the effects of poverty, Katrina’s trauma and trauma afterward.

Redlener’s group has been studying 1,079 families in Louisiana and Mississippi since February 2006, six months after Hurricane Katrina. In the latest interviews, from November through March, each family was asked about a child with the most recent birthday.

He found that 36 percent of those 427 children met federal criteria for serious emotional disturbance. That’s 4.5 times more likely than children from similar families in a national study in 2004, according to the report.

About half of the households either were living in transient housing or had no guarantee that they’d be in their current quarters for more than a year.

And 52 percent of the parents or caregivers thought their children needed professional help, but couldn’t get it because they didn’t know where to go, didn’t have insurance, transportation, an available therapist or child care for other children.

The groups overlapped, but at least 60 percent had at least one of the problems for the estimate of at least 20,000, Redlener said.

In separate research, Osofksy has looked at about 5,000 fourth- through 12th-grade children screened last year in St. Bernard, Plaquemines and Orleans parish schools. Of that group, 31 percent showed some symptoms of depression or post-traumatic stress, but only 12 to 15 percent asked for individual or group counseling. The school-based program doesn’t diagnose children, she said.

Redlener wants more mental health services available to children, government action to get the families into safe and stable housing, and more support for the families. He also says governments need to quickly collect information about children and families hurt by disaster and to ensure they can be helped as long as they need it.

‘‘We know governments, state and federal, are dealing with a very deep recession, and available cash to provide support for these recommendations is extremely limited,’’ he said.

On the other hand, he said, ‘‘It’s pay now or pay later — and the ’later’ is extraordinarily expensive.’’