Since Thursday, thousands of migrants have crossed from Morocco into the North African Spanish enclave of Ceuta.
The latest estimates by the Spanish government set the number at around 60,000.
If the figures are confirmed, the event would be the largest single surge in irregular arrivals ever recorded on EU territory.
Most migrants came by sea, swimming from the Moroccan border town of Fnideq. They reached several beaches, especially El Tarajal, one of the closest to the border.
At least 18 people have died in the attempt until Friday morning, the Associated Press reports, many of whom in a stampede while trying to cross breakwater fences.
