The Moroccan navy on Tuesday rescued 63 migrants including 15 women and three children after their vessel started to sink as they tried to reach the Canary Islands, activists said.

Alarm Phone, which provides an emergency hotline for migrants in trouble at sea, said on Twitter that "63 people in severe distress close to the Moroccan coast were found by the Moroccan navy and safely brought to shore."

The Moroccan authorities did not immediately confirm the operation.

Helena Maleno Garzon of rights group Caminando Fronteras had earlier warned that dozens of people were sinking in an inflatable boat off Tarfaya, on Morocco's southern coast, and would "die if they are not rescued soon".

Migrants, mostly from sub-Saharan Africa, regularly use Morocco as a launchpad for attempts to reach European shores.

Last year more than 4,000 migrants died or went missing in such attempts, mostly as they tried to reach the Canary Islands, according to Caminando Fronteras.

Many choose to head for the Spanish territory in the Atlantic as shorter routes across calmer Mediterranean waters are more closely monitored, the group says.