The death toll from a migrant boat disaster off Djibouti this week has risen to 24, the UN's migration agency said, highlighting a sharp increase in the number of people returning from Yemen to the Horn of Africa nation this year.

The capsize on Monday was the second fatal maritime accident in two weeks off Djibouti, which lies on the perilous so-called Eastern Migration Route from Africa to the Arabian Peninsula.

At least 24 people died and 20 remain missing after the boat carrying at least 77 migrants including children capsized near the town of Obock, the International Organization for Migration said late Wednesday.

It said 33 survivors are being cared for at an IOM centre in Obock and that local authorities are conducting search and rescue operations in the hope of finding more people alive.

Addis Ababa's ambassador to Djibouti had said those on the boat were Ethiopian migrants.

Another vessel also carrying mainly Ethiopian migrants sank in the same area on April 8, with a death toll of at least 38.

"The occurrence of two such tragedies within a span of two weeks highlights the dangers faced by children, women, and men migrating through irregular routes, underscoring the importance of establishing safe and legal pathways for migration," IOM chief of mission in Djibouti, Tanja Pacifico, said.

The IOM said it had recorded a total of 1,350 deaths on the Eastern Route since 2014, not including this year.

In 2023 alone, it said it documented at least 698 deaths along the route including 105 lost at sea.

- 'Immense challenges' -

The agency said it was believed that the people on both ill-fated vessels were attempting to return from Yemen to Djibouti after failing to reach Saudi Arabia.

Each year, many tens of thousands of African migrants brave the Eastern Route across the Red Sea to try to reach oil-rich Gulf nations, escaping conflict or natural disaster, or seeking better economic opportunities.

However, many are unsuccessful and "thousands are stranded in Yemen where they experience extremely harsh conditions", the IOM said.

Since the start of 2024, the agency said 3,682 migrants have left war-torn Yemen for Djibouti, more than double the figure for the same period last year.

"This sharp increase is due to the immense challenges and difficulties in Yemen and in reaching the Kingdom of Saudi Arabia," it added.

In August, Human Rights Watch accused Saudi border guards of killing "at least hundreds" of Ethiopians trying to cross into the Gulf kingdom from Yemen between March 2022 and June 2023, using explosive weapons in some cases.

Riyadh dismissed the group's findings as "unfounded and not based on reliable sources".