Moroccan authorities said they were investigating the collision, but Spain’s interior ministry said it would not.
Aina Vidal, the parliamentary spokesman for Sumar, the junior partner in Spain’s Left-wing coalition Government, called the collision an “intolerable human disaster”.
Sumar and other parties called for an official explanation from Fernando Grande-Marlaska, the interior minister.
Authorities in Morocco have said the vast majority of attempts to smuggle migrants by boat into Melilla and Ceuta, Spain’s other North African territory, involve traffickers based in the Spanish cities.
Spain’s two enclaves on Morocco’s Mediterranean coast, Ceuta and Melilla, share the only land borders of the European Union with Africa. The enclaves sporadically experience waves of attempted crossings by migrants trying to reach Europe.