ADDIS ABABA - Ethiopia has appealed for international help after the death toll from a devastating series of floods this month rose to some 870.
"The situation is beyond the capacity of our region, and we appeal to the international community to come to our assistance," said Southern Regional Administrator Shesaraw Shegute after flying over the devastated area in a helicopter.
The government warned of more floods in all areas.
"The country's major hydropower dams are holding more water than required and could spill over their banks causing heavy destruction to adjoining areas," said a joint statement from the Ministries of Mines, Information and Water Resources.
The statement added that more rivers in the north, south, east and west had burst their banks "threatening to submerge development projects in their respective areas."
Rescuers discovered 170 more bodies on Wednesday three days after the Omo River burst its banks.
"Rescuers using motorboats and helicopters picked 170 more bodies out of the swollen Omo river which broke its banks and submerged surrounding villages, bringing the death toll there to 364," Inspector Daniel Gezahenge told Reuters.
"Under the circumstances it is expected that more bodies will be discovered because the flood has spread over wide areas," added Gezahenge, spokesman for the southern regional police force.
That lifted to around 870 the total feared dead in floods in the Horn of Africa nation this month.
Thousands also remain stranded, cut off by massive floods and desperate for food and shelter in the remote south, where the Omo river overflowed, the United Nations and Ethiopian government said.
"There is no access to the area. The roads are not passable, and because of heavy clouds even helicopters cannot move," Vincent Lelei, deputy head of mission for the UN office for humanitarian affairs (OCHA) in Ethiopia, told Reuters.
"The visibility is very poor," he added.
State television said two army helicopters and 14 motorboats had been deployed to evacuate up to 6,000 people marooned by the floods, but bad weather has been hampering rescue efforts.
After suffering a drought since late last year, heavy rains have been battering Ethiopia in recent weeks.
In the east, the Dechatu river burst its banks last week, killing 254 and leaving 250 missing and feared dead in the Dire Dawa, 525 km (324 miles) east of the capital.
Officials and aid workers say the numbers of dead and homeless could turn out to be much higher due to the inaccessibility of the regions worst affected.
The local populations are mainly nomadic herders.
Regional administrator Shesaraw said most of the pastoralists in the affected area lost their entire livestock.
As well as the Omo and Dechatu disasters, officials fear the overflowing Awash River, some 300 km (190 miles) east of the capital, could soon burst its banks too.
The Awash Valley is home to three major sugar estates. Some 7,000 people near the riverbank are being evacuated.
Floods typically occur in lowland areas after heavy rains in the June-August rainy season drench the country's highlands.
Heavy rains and snow also fell on South Africa's southern region on Wednesday, blocking roads and spurring rescue attempts to save stranded motorists.