Some 40 migrants have drowned after their boat sank off Morocco's northern coast on Sunday, local media reported.

The dead migrants are from sub-Saharan African countries, and a number of them are women, the Moroccan Alyaoum24.com news site said.

The bodies of the migrants were sent to the morgue of a local hospital, in the city of Larache, the report said, adding that an investigation is underway to determine the exact circumstances of the accident.

Morocco has become a hub for African migrants who seek to reach Europe for a better life. Thousands of migrants are trying to flee poverty and unrest in Africa each year via Morocco to Europe, either by land into the Spanish enclaves of Ceuta and Melilla or by sea often in flimsy vessels.

According to Morocco's Interior Ministry, security forces arrested some 50,000 migrants in 2017 and dismantled over 70 organized illegal migration networks.