The crowded rubber vessel was carrying more than 100 would-be migrants, mostly from sub-Saharan Africa, officials say.

A search is under way for survivors but Moroccan authorities say most of those aboard the boat made it ashore safely.

Thousands of illegal immigrants attempt the risky sea crossing from Morocco to Spain every year, correspondents say.

Many drown during the journey.

Local police say four members of the Moroccan coast guard have been arrested in connection with the latest deaths.