The United Nations says unrest in Yemen has hampered the activities of humanitarian teams [EPA]

The United Nations refugee agency has raised concerns over the record numbers of Ethiopians and Somalis flocking to Yemen, despite the deteriorating security situation there.

Last year, 103,000 refugees, asylum seekers and migrants crossed the Gulf of Aden and Red Sea, with a reported 130 of them drowning in transit. The number of refugees almost doubled the 2010 figure of 53,000.

Most refugees arrive dehydrated and malnourished, only to face physical and sexual attacks and trafficking, Adrian Edwards, a spokesman for the UN High Commissioner for Refugees, said on Friday at a briefing in Geneva.

"Instability and the reduced police presence in Yemen are giving human traffickers and smugglers more room to operate," said Edwards, who said the situation was also hampering the activities of humanitarian teams.

Somali refugees recently accounted for the majority of all arrivals in Yemen, but Ethiopian migrants have since become the largest group.

Three Ethiopians were reportedly killed while trying to escape from smugglers in Taiz governorate on January 13, he said.

Somalis say conflict, insecurity, drought and famine are driving them out of their country, while Ethiopians cite a lack of economic opportunities and go to Yemen to try to reach other Gulf states.

They are regularly robbed and attacked by smugglers and traffickers who try to extort money from them.

Yemen, one of the world's poorest countries, has become increasingly unstable following months of mass protests against the government of President Ali Abdullah Saleh.