UNITED NATIONS — The majority of the world’s some six million refugee children are not in school, making them five times less likely to get an education than the global average, the U.N. warned Thursday.

A full 3.7 million school-aged refugee children have no school to go to, the UN refugee agency said in a report.

“This represents a crisis for millions of refugee children,” UN refugee chief Filippo Grandi said in a statement, urging international action to get the children back to school.

His comments came ahead of the first-ever U.N. summit on refugees and migrants, to be held in New York on Sept. 19, and which will be followed the next day by a pledging conference for new offers of aid to refugees hosted by President Obama.

“As the international community considers how best to deal with the refugee crisis, it is essential that we think beyond basic survival,” Grandi said, pointing out that refugees on average are displaced for about 20 years.

That, he said in the UN report, “is more than an entire childhood.”

“Education enables refugees to positively shape the future of both their countries of asylum and their home countries when they one day return,” he stressed.

Thursday’s report, which compares UNHCR data on refugee education with data from UNESCO on global school enrollment, showed that only 50 percent of the world’s refugee children have access to primary education.

That compares to a global average of more than 90 percent.

“And as these children become older, the gap becomes a chasm,” it said, pointing out that only 22 percent of teens living as refugees attended secondary school.

That compares with a global average of 84 percent.

As for university, only one percent of refugees attend, compared to 34 percent globally, the report showed.