At least 21 migrants drowned, while 23 remain missing after a boat carrying 77 people capsized off the coast of Djibouti, the United Nations migration agency said Tuesday.

In the second such incident in two weeks, the boat's occupants included children, the International Organization for Migration (IOM) said in a post on social media platform X.

Tens of thousands of migrants from the Horn of Africa, especially from Ethiopia and Somalia, leave the continent through Djibouti, aiming to reach Saudi Arabia and other Gulf nations to find work, according to IOM.

Many fail, and thousands are stranded in Yemen where they live in harsh conditions, IOM says. Drownings are common in the waters off Djibouti as the migrants make their journeys.

Tanja Pacifico, the head of its Djiboutian office, said Tuesday's death toll had risen from an earlier figure of 16 IOM had given.

Another 33 people were rescued from the water, she said, adding that they and all the dead were Ethiopians.

"What is exceptional is that is we had another shipwreck with 38 Ethiopian nationals just less than two weeks ago," Pacifico told Reuters by phone.

At least 38 people, including children, died in that shipwreck off the Djibouti coast.

She said Tuesday's capsized boat was sailing to Djibouti from Yemen.