The UN refugee agency said Saturday it was alarmed by a suspected measles outbreak in south-east Ethiopia's Dollo Ado camps, where thousands of famine-hit Somalis have sought refuge in recent weeks.

"UNHCR fears the outbreak could lead to high mortality and serious illness in an already vulnerable refugee population whose overall health was already fragile," said the office of the UN High Commissioner for Refugees in a statement.

On August 4, health workers reported 25 deaths in the Kobe camp, of which half were suspected to have arisen from measles, said the UNHCR.

Other cases have also been reported in other camps in the surroundings.

Measles rarely kills healthy individuals but can be fatal to malnourished people.

"This situation is alarming and we cannot afford to wait," warned Moses Okello, UNHCR Ethiopia representative.

"We must act now, urgently and decisively, to arrest and turn around this situation," he said, adding that a campaign to vaccinate children was essential.

A team of experts are expected to arrive in Dollo Ado on Sunday to support a vaccination campaign which is to begin August 9.

The Dollo Ado camps host 118,400 Somali refugees, including 78,000 who arrived this year after fleeing violence and what the UN has described as the region's worst drought in decades.