More than 20,000 Africans have fled across the Gulf of Aden to Yemen this year, twice as many as during the same period in 2007, an aid agency has said.
Medecins Sans Frontieres said that almost 700 people had died so far as they attempted to reach Yemen by boat.
Security in Somalia has been deteriorating, causing more and more people to flee the country.
Ethiopian troops, in Somalia to support the government there, said they killed at least 71 insurgents this week.
Dozens of people have been reported killed in heavy fighting in Somalia this week.
Islamist insurgents clashed with government forces and their Ethiopian allies in the capital, Mogadishu, and the central location of Mataban and Guri Eal near the border with Ethiopian.
Some of the insurgents are remnants of the Islamist administration, which ruled much of southern Somalia in 2006, while others are nationalists who see the Ethiopians as invaders.
Many of those displaced have risked the hazardous boat trip across the Gulf of Aden.
Dozens of Somalis have been arriving each week in the Kharaz refugee camp in the south of the country, the BBC’s Stephanie Hancock reports from southern Yemen.
Isolated in a barren desert valley, the camp is a place nobody would come to by choice, she says.
One refugee, Faduma Ahmat Hassan, said her husband and son had been killed coming out of a mosque, and she had gone to collect her son’s body.
« As I cried next to his corpse the troops took me away, » she said.
« They raped me for 24 hours and when they brought me back, I was unconscious. »
Another refugee was struggling to look after his two infant children after his wife died from dehydration on the boat ride over.
« The children always ask me where their mother is but I haven’t told them the truth yet, » he said.
Recent violence in Somalia has come despite a ceasefire pact signed by the government and opposition Islamist groups last month.
Some factions rejected the deal.
This week’s battles in Somalia involved a large group of Ethiopian troops – one well-informed source told the BBC it may have been as many as 1,200 soldiers.
Reports from the area say destitute local people – many of whom had earlier fled Mogadishu and see Ethiopia as partly responsible for their plight – refused to co-operate with the foreign troops and that heavy clashes followed.
The insurgents say they killed 10 Ethiopian troops. The Ethiopians say they killed 71 of their opponent attackers, including a well-known member of Union of Islamic Courts, known as Asparo.
Somalia has experienced almost constant civil conflict since the collapse of Mohamed Siad Barre’s regime in January 1991.
The UN has warned that nearly half of Somalia’s population is likely to require aid later this year.