Six people were found dead and 29 are missing and presumed dead after their boat capsized off the coast of Libya, the International Organization for Migration (IOM) said Saturday.

"A small wooden boat carrying around 35 migrants capsized off Sabratha, #Libya yesterday," the IOM tweeted.

"The bodies of six people have been retrieved while 29 others are missing and presumed dead. At least 53 migrants have been reported dead or missing off Libya this week alone."

Libya, wracked by a decade of conflict and lawlessness, has become a key departure point for African and Asian migrants making desperate attempts to reach Europe.

Migrants often endure horrific conditions in Libya before boarding overcrowded, often unseaworthy vessels that frequently sink or run into trouble.

The United Nations' refugee agency UNHCR has said that around 1,300 migrants drowned or went missing in the central Mediterranean in 2021, making it the world's deadliest migration route.

The UN migration agency said Monday that four people were killed and 14 others missing after another boat sank off Libya's coast, while two people were rescued.

"At least 475 people have died attempting to cross the central Mediterranean so far this year," it said.

Earlier in April, nearly 100 people died in international waters after setting off from Libya in an overcrowded boat.

Four people survived the incident, which was described as a "tragedy" by the UN refugee chief.