At least 45 migrants, including five children, have died in the deadliest shipwreck off Libya so far this year, the UN's agency for refugees says.

They were among more than 80 people on board a vessel whose engine exploded off the coast of Zwara, the UNHCR said.

The deaths were reported by some 37 survivors rescued by local fishermen.

Both the UNHCR and International Organization for Migration (IOM) have called for search and rescue efforts for migrants to be stepped up.

They said that without a dedicated search and rescue operation mechanism, more lives would be lost in the Mediterranean.

The survivors, who were mainly from Senegal, Mali, Chad and Ghana, were detained after they disembarked in Libya.

The UNHCR and the IOM said that Libya was not a safe destination to return migrants to as they were "at risk of the ongoing conflict, severe human rights violations, and arbitrary detention post-disembarkation".

More than 300 people are known to have died trying to cross the sea from Libya to Europe this year, with the actual figure believed to be much higher.
bbc