A survey shows about 70 percent of child refugees staying in Greece do not attend school.
Many refugees from civil war-torn Syria and other countries have gone to Greece on their way to Western Europe. Most of them hope to go to richer countries, such as Germany and the Nordic nations.
But as some European nations began to tighten border controls 2 years ago, refugees have increasingly been stuck in Greece. The number of refugees has amounted to about 60,000.
With financial aid from the European Union, the Greek government opened special classes at elementary and junior high schools in October of last year to teach refugee children the Greek language.
The UN children's agency UNICEF says its survey shows that among 12,000 children aged 6 to 17, about 8,500 did not attend the classes as of June.
The agency says one reason is that parents do not want their children to learn Greek, because they wish to go to richer countries rather than settling in financially struggling Greece.
But some countries are rejecting EU quotas for refugees.
UNICEF officials point to the challenge of how to secure educational opportunities for child refugees.