New Delhi, Aug. 21 -- For weeks, migrants in the Spanish territory of Ceuta had gathered on a beach away from the city center, sleeping on cardboard sheets, under reed huts and guarding their few possessions in tattered plastic bags.

They were gone by Thursday morning after Spanish police escorted them to makeshift shelters. But an hour later, other migrants were combing through the trash they had left behind for anything useful: an abandoned mattress, plastic chairs, sheets, a scrap of tarp.

The scene exemplified the ongoing humanitarian crisis in Ceuta, where up to 10,000 migrants remain in the city weeks after more than 72,000 people poured into the small Spanish territory neighboring Morocco. Three weeks later, Spanish authorities w...