"The number fleeing from the fighting into neighbouring countries has doubled in the past month," the UNHCR said in a statement in the Kenyan capital Nairobi.
More than 400 refugees a week have reached Lokichokio in northwest Kenya so far this month, while 900 fled into neighbouring Uganda in the first three weeks of March.
In 10days in January, 5,500 refugees fled into Ethiopia to escape fighting between rival rebel groups in Sudan's Blue Nile province.
About 500,000 Sudanese refugees are now registered with the UNHCR, most of them in countries bordering Sudan. Over 50,000 of them fled Sudan last year, mainly to Kenya, Chad, Ethiopia and Uganda.
Over 1.5 million Sudanese have died from violence, famine and other causes in the war between southern rebels and the Khartoum government since 1983.
The Sudan People's Liberation Army spearheads the struggle for autonomy by the Christian and animist southerners against the Islamist Khartoum government. But there have also been splits between the rebel groups, frequently erupting into armed clashes. Banditry is also common.
- Reuters - Thomson Reuters Foundation
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