The UN refugee and migration agencies said in a joint statement on Friday that there were at least 152 Somalis and Ethiopians on board the overcrowded boat which departed from Aden in southern Yemen on 23 January.
"The vessel is believed to have been operated by unscrupulous smugglers who were attempting to take refugees and migrants to Djibouti, while also trying to extort more money from these refugees and migrants," the statement added.
The vessel "capsized amid reports of gunfire being used against the passengers", the UN agencies said, adding that it was working with the Yemeni coast guard to try to find out what happened.
"At least 30 people have died in this tragic incident" which occurred near the coast, the statement said.
At least 13,600 people have been killed since Saudi Arabia launched a military campaign against Yemen in an attempt to reinstall Abd Rabbuh Mansur Hadi, Yemen’s former president and a staunch ally of Riyadh, and to crush the Houthi Ansarullah movement. The Saudi campaign, however, has failed to achieve its goals.
The UN Refugee Agency said it was "outraged" by the latest casualties.
"Prolonged conflict and insecurity in Yemen continues to expose vulnerable refugees and migrants to heightened risks of human rights violations including arbitrary arrest, detention, trafficking and deportation," the agency tweeted.
Last August, scores of African refugees died after they were forced from two boats into rough seas off Yemen by smugglers.
Yemen’s lawless southern regions, which are mostly controlled by militants loyal to Saudi Arabia and Yemen’s resigned president Abd Rabbuh Mansur Hadi, have become a fertile ground for smugglers who vow to transfer refugees from the region to wealthier Arab states in the Persian Gulf.
However, most of those smugglers leave refugees at sea as they fear being arrested by militants or Saudi Arabia’s military forces.