The president of Gambia is calling for a United Nations investigation into what he calls the "man-made sinking" of boats carrying African migrants to Europe.

President Yahya Jammeh on Thursday used his address to the annual U.N. General Assembly of world leaders to blame the deaths of more than 500 Gambians over the past five years on the "very dangerous, racist and inhuman behavior of deliberately causing boats carrying black Africans to sink."

International organizations estimate that more than 20,000 people, mostly from Africa and the Middle East, have died in the past two decades trying to reach the Italian coast.

Gambia's autocratic ruler is known for his striking statements at the U.N. In his address last year, he called homosexuality one of the three "biggest threats to human existence."