Several Nigerians are reported to be among those who drowned as several persons trying to cross the Mediterranean Sea into Europe fell into the water last week.
No fewer than 14,000 migrants were rescued in the process.
According to Medicines San Frontieres and the United Nations High Commission for Refugees, between 700 and 900 migrants, including Nigerians, drowned during boat mishaps at the Mediterranean Sea last week.
Both MSF and the UNHCR said last week was the busiest for migrants leaving Libya to Italy in 2016.
About 14,000 have been rescued since Monday.
“We will never know exact numbers,” Medecins San Frontieres said in a tweet after estimating that the number of deaths stood at 900.
The UNHCR said more than 700 had drowned.
Those who arrived in Europe already included Eritreans, Sudanese, Nigerians and many other West Africans, according to the agencies.