"Flash floods following heavy rains for nearly a week have caused major rivers in Gambella to burst their banks, submerging residential areas and farmlands and forcing 18,000 people to be displaced", said Akway Ojulu, head of emergency assistance in Gambella.

"So far we have reports of the deaths of three people including one child," he told Reuters by telephone.

Ethiopia faces seasonal flooding between June and September. Flash floods typically happen in lowland areas of the country after heavy rains drench the highlands during the rainy season.

According to the United Nations, more then 100,000 people were affected by floods in Ethiopia last year and 17 died of waterborne diseases.

Akway said crocodiles had hampered rescue efforts.

"We are taking precautions, but the vast number of crocodiles swarming the Gilo river may harm unsuspecting people," he said.

About 3,000 hectares of farm land with maize, sorghum and cotton have been destroyed by the flood water, he added.

"Indications are there will be continued heavy rains in the coming weeks to hit Gambella," he said.

Akway said the federal and the regional governments had offered food assistance to the displaced.

"But there is great need for shelter, blankets and cooking utensils for the displaced people who are living in open air and under trees," he said.