Dozens of Africans were feared drowned off south Yemen, the interior ministry and a security official said on Monday amid conflicting reports over their numbers and the cause of the accident.

"Eighty Africans, mostly Ethiopian, drowned after their two boats were capsized," said an interior ministry statement.

"The accident was caused by high winds and a tsunami which capsized the two boats taking them towards the coast," the statement said, quoting the coast guard in the southern port city of Aden.

One boat with 46 migrants aboard, most of them Ethiopians, "capsized in a coastal region... of Taez province, with all those on board drowning except for three Somalis who survived," it said.

Another boat carrying "between 35 to 40 people, all of them Ethiopians and among them women and children" went down off the coast of another southern province, Lahij, the ministry said.

"Their fate is not yet known," it said, adding that a search was under way.

However, the security chief of Bab al-Mandab strait that links the Red Sea and the Gulf of Aden put the number of people missing at 35.

Five Ethiopians survived along with two Yemeni people smugglers, he said.

The official, who said that only one boat capsized, said the accident was caused by engine damage.

Each year tens of thousands of Ethiopians and Somalis make the perilous crossing to Yemen in the hope of escaping the economic deprivation, persecution and conflicts of their home countries.

Many die on board often overcrowded and rotten small boats, while others, already weakened by long journeys from the hinterland to the coast, die at the hands of ruthless smugglers.

The migrants generally slip by boat into south Yemen, itself one of the world's poorest countries, before heading towards the border with oil-rich Saudi Arabia.

The United Nations High Commissioner for Refugees said last April that the exodus of Somalis across the Gulf of Aden had slowed dramatically since the start of 2010, despite recurring violence in Somalia.