Most of the migrants had returned to Morocco within 48 hours of crossing, but the incident has raised alarm among European leaders about the bloc's shared border security.Ceuta has steadily fortified its border over the years as it became a key route for migrants trying to reach Europe.The Spanish exclave already had a border fence with Morocco, but Spanish authorities have since begun installing a 500m-long floating barrier on its sea border with its African neighbour It said order had been restored within 24 hours and that reinforced police and military deployments would remain for as long as necessary.Hundreds of migrants continued to make their way back to Morocco on Saturday, some saying they had done so voluntarily, leaving Ceuta after what they described as degrading treatment on the Spanish side of the border.They walked along a long stretch of beach before slipping into Morocco through a small breach in the border fence