All children under five have died in a refugee-packed Sudanese town where the United States has begun an airlift of food and medicine, relief workers said.

The first mercy flights were shuttling into Abyei in southern Kordofan province where relief agencies said a generation has been wiped out by starvation and malnutrition."Immediate airlift was decided upon for Abyei and other locations because food stocks are below what is necessary to sustain the numbers there," an official for the USAID relief agency said on Friday.

Abyei's population has swelled to around 100,000 with the arrival of 25,000 refugees from the Dinka tribe fleeing the surrounding bush to escape harassment by Arab militiamen, flood and famine exacerbated by five years of civil war, the relief worders said.

But the situation in the town is little better.

Roads into Abyei have been made impassable by heavy floods and aircraft ferrying supplies can only carry a tonne at a time.

A USAID official said only 18 tons of relief aid had so far reached Abyei, 420 miles from Khartoum.

Each of the chartered Nile Safaris' relief aircraft is making three trips a day to the town where USAID plans to deliver a total of 90 tons of food and medicine in a million dollar operation.

More aid will be sent by road when the floods subside.

USAID eventually plans to set-up a trans-shipment point further south and closer to the famine hit areas.

The relief agency says it is planning mercy flights to other parts of southern Kordofan, including el-Meriam and Muglad.

Rebels of the Sudan People's Liberation Army (SPLA) have been fighting government forces in mainly Christian and animist southern Sudan since 1983 to end what they see as excessive Arab Moslem influence from the north.

The fighting has cut-off southern areas near the Ugandan border with roads mined and frequently ambushed by rebels.

Aircraft have been attacked and one ferrying relief supplies to the town of Juba was recently machine gunned as it landed.