At least 43 migrants from West Africa perished in the first major shipwreck off the Libyan coast this year, the United Nations said Wednesday, adding that 10 people were rescued.

The UN agencies for refugees and for migration said they were "deeply saddened" by the tragedy.

The shipwreck, they said, happened Tuesday after a boat that set off from the city of Zawya capsized just a few hours after departure when its engine stopped in poor sea conditions.

Survivors, who were mainly from the Ivory Coast, Nigeria, Ghana and Gambia, said those who perished were all men from West African countries, the UN agencies added.

The shipwreck was the first of 2021 off Libya, but comes after hundreds of people lost their lives last year trying to cross the central Mediterranean to Europe -- making it the most deadly migration route in the world.

In their statement, the International Organization for Migration (IOM) and the UNHCR said they feared that "due to the limited ability to monitor routes", the actual number of deaths last year "could be much higher".

"This loss of life highlights once more the need for re-activation of state-led search and rescue operations, a gap NGO and commercial vessels are trying to fill despite their limited resources," they said.

The agencies also reiterated their call on the international community to urgently shift its approach to the situation in the Mediterranean.

Map of Libya locating shipwreck where a number of migrants drowned
Map of Libya locating shipwreck where a number of migrants drowned AFP / Paz PIZARRO

"This includes ending returns to unsafe ports, establishing a safe and predictable disembarkation mechanism followed by a tangible show of solidarity from European states with countries receiving high numbers of arrivals," the statement said.

Libya has become a key route for irregular migration to Europe in the chaotic years since the 2011 overthrow and killing of dictator Moamer Kadhafi in a NATO-backed uprising.

While many have drowned at sea, thousands have been intercepted by the Libyan coastguard, which has been backed by Italy and the EU, and returned to Libya.

They mostly end up in detention, often in horrific conditions.

"The situation for migrants and refugees in Libya remains extremely precarious," the UN said Wednesday.

"Arbitrary arrests and arbitrary detention in the direst of conditions continue. Many are victimised and exploited by traffickers and smugglers, held for ransom, tortured, and abused."

While acknowledging efforts made by Libyan authorities to combat smuggling and trafficking, they called for increased efforts to hold perpetrators accountable.

"Should inaction and impunity prevail, more avoidable and tragic loss of life can be expected," they said.