The IOM said the bodies of six migrants were withdrawn, while 29 others were missing and presumed dead. It was not immediately clear what caused the wooden boat to capsize.

The tragedy was the latest involving migrants who left North Africa to seek a better life in Europe. At least 53 migrants were reported dead or presumed dead off the coast of Libya in the past week alone, according to the IOM.

“Dedicated search and rescue capabilities and a secure disembarkation mechanism are urgently needed to prevent further death and suffering,” the IOM said.

Investigators commissioned by the United Nations’ highest human rights body have found evidence of possible crimes against humanity committed in Libya against migrants held in government-run prisons and at the hands of human traffickers.

More than 90 people drowned in an overcrowded boat in the Mediterranean Sea earlier this month, according to aid group Doctors Without Borders, days after leaving Libya.

Migrants regularly try to cross the Mediterranean from Libya in a desperate attempt to reach European shores. The country has emerged as the dominant transit point for migrants fleeing war and poverty in Africa and the Middle East.

People smugglers have taken advantage of the chaos in Libya in recent years by smuggling migrants across the oil-rich country’s long borders of six countries. The migrants are then usually packed into poorly equipped dinghies and embark on risky sea voyages.

At least 476 migrants died along the central Mediterranean route between January 1 and April 11, according to the IOM.

Once back in Libya, the migrants are usually taken to government-run detention centers where there is a lot of abuse and ill-treatment.