An agreement has been reached with Ethiopia’s government to provide emergency supplies to the predominantly Somali Ogaden region, the UN says.
Fighting between separatist rebels and the army resulted in accusations that the authorities were preventing aid supplies from reaching the area.
A security assessment of the area will now be undertaken by the UN, followed by the establishment of two bases.
From these bases, aid will be delivered to an estimated 640,000 people in need.
Trouble started in the region in April when fighters of the Ogaden National Liberation Front (ONLF) attacked a Chinese-run exploration team, killing 74 people.
These developments are very good news for the people of the region
UN’s Fidele Sarassoro
The ONLF accused the authorities of imposing a blockade on the area, choking off commercial trade.
In September, the aid agency Medecins Sans Frontiers said it had been denied access to the barren region – two months after the Red Cross was ordered to stop operations there.
But it is reported that access to the eastern region has recently improved.
"The Ethiopian government has assured the UN that humanitarian activities within Somali region will be unrestricted," said the UN’s Fidele Sarassoro, after what were described as tough negotiations.
"These developments are very good news for the people of the region. We applaud the excellent collaboration we have seen thus far."
The ONLF was founded in 1984 and is fighting for independence from Ethiopia, complaining of discrimination by the central government against the region’s Somali-speaking nomads.