Yemen has detained more than 10,000 illegal African immigrants in 2005, mostly from Somalia, the official Yemeni news agency has reported.
The report says that more than 100 migrants have drowned in September alone trying to reach the country.
The agency says 10,750 people had been seized in Yemeni cities and on the coast, which faces the Horn of Africa.
The Somalis are held at a detention camp in the southern Abyan province. Other Africans have been repatriated.
Correspondents say Somalis fleeing violence and Ethiopians in search of a better life attempt the hazardous 300-km (185-mile) crossing to Yemen in the hope of eventually reaching the oil-rich Gulf Arab region and Europe.
Yemen is a poor country of approximately 20 million people.
The UNHCR, the United Nation's refugee agency, says the number of Africans trying to get into the Gulf region via Yemen has increased since early 2004.
It puts the number of registered Somali refugees in Yemen at about 50,000.