The Greek government says it has completed work on most of the migrant facilities it has promised its European Union partners to deliver.

But Defense Minister Panos Kammenos says the centers might not have to function to their full capacity of 24,000 people because an agreement to involve NATO in policing Greece's sea border with Turkey will "end the immigration problem."

Greece is the main gateway for people from the Middle East, Asia and Africa seeking a better life in Europe. About 77,000 people have reached the country's eastern islands this year from nearby Turkey, paying smugglers for a berth on frail boats.

Government officials said Tuesday that four of five promised reception and screening centers on the islands are now functional, and the last will be ready in days.