Twenty-nine people are reported to have died after they were pushed into the sea off Yemen by a people smuggler.
More than 120 of the Somali and Ethiopian migrants were deliberately shoved into the water by a smuggler worried about being arrested, according to the International Organization for Migration (IOM).
The dead included women and children.
The organisation said it had found their shallow graves, dug by survivors, on a beach in southern Yemen along the Gulf of Aden.
IOM spokeswoman Olivia Headon said: “They were all quite young, the average age was around 16.”
Another 22 people are missing and 27 survived. Others are understood to have fled.
“The survivors told our colleagues on the beach that the smuggler pushed them to the sea, when he saw some ‘authority types’ near the coast,” said Laurent de Boeck, the IOM Yemen chief of mission.
“They also told us that the smuggler has already returned to Somalia to continue his business and pick up more migrants to bring to Yemen on the same route.
“This is shocking and inhumane.The suffering of migrants on this migration route is enormous.
“Too many young people pay smugglers with the false hope of a better future.”
The migrants, travelling to Yemen in search of new opportunities in the Gulf, had travelled a route taken by 55,000 others from their region this year.
The news came as Italy gave permission to the Spanish humanitarian ship Golfo Azzurro to dock and allow three rescued migrants to disembark in Sicily.
The decision came after a three-day standoff between Italian authorities and their Maltese equivalents over who should accept the rescued men.
The Golfo Azzurro, which was chartered by Spain’s Proactiva Open Arms NGO, had rescued the three Libyan men on Sunday.
But when it approached Lampedusa, an Italian island, the Italian officials refused them permission and said the rescue had taken place in Malta’s search and rescue zone.
Malta also refused to accept the men, saying they were Italy’s responsibility.
The men got off the ship in Pozzallo, Sicily, where they plan to apply for asylum.