At least 150 people have drowned after their boat sank off the Libyan coast Thursday, the UN Refugee Agency (UNHCR) confirmed, reports CNN.
Around 300 people are believed to have embarked on the dangerous sea crossing from the Libyan port city of Al-Khums, 80 miles east of Tripoli, UNHCR spokesman Charlie Yaxley said.
The vessel got into trouble in the waters off the coast of Libya. Some passengers were rescued by local fisherman, who were later joined by the Libyan coastguard, he added.
"More than 600 people have now lost their life on the Mediterranean Sea this year," Yaxley said. "If current trends continue, we are likely to see more than a thousand people lose their life on the Mediterranean for the sixth year in a row, which is a bleak milestone for us to be reaching."
The Libyan branch of the International Organization for Migration (IOM) also tweeted on the incident, posting that 145 were rescued.
"The worst Mediterranean tragedy of this year has just occurred," said Filippo Grandi, the UN High Commissioner for the UNHCR.
Each year, thousands pour across Libya's borders -- the final stop before a short but treacherous sea voyage across the Mediterranean to Europe.
With dreams of finding better opportunities, migrants are often exploited for vast sums by traffickers and packed onto almost unseaworthy vessels for the dangerous crossing.
As reports emerged of the latest tragedy in the Mediterranean, several human rights organizations called on Libya to shutter its controversial migrant detention centers.
UNICEF Executive Director Henrietta Fore said the migrants saved from Thursday's shipwreck "now face an uncertain fate as they are returned to detention in Libya, where violence in Tripoli in recent months has made the situation increasingly desperate and dangerous."
Fore continued: "I echo the UN High Commissioner for Refugees, Filippo Grandi and the Director-General of IOM, António Vitorino's urgent call to restore search and rescue efforts in the Mediterranean, to end arbitrary detention and ensure refugees and migrants in Libya have pathways out of detention centers to urban areas, to open centers, or out of the country."
"Without urgent action, we will continue to see children lose their lives making these journeys," she added.