ADDIS ABABA - Ethiopia braced for more damage from deadly nationwide flash floods as the government warned that unusually heavy seasonal rains could force the release of water from dangerously swollen dams.

A task force set up to deal with flooding crises that have affected nearly 75,000 people said three dams in the west, south and north of the country were close to the breaking point and advised residents in their vicinities to leave.

It said that, although controlled, the release of water from the threatened dams on the Omo, Awash and Blue Nile rivers could compound devastation from floods that have already killed at least 626 people in the south, east and north.

"Currently, the main dams are planning to release some waters, and the national task force is advising people living near the dams and downstream to take precautionary measures and, if possible, move to higher ground," it said Sunday.

The facilities are the Gilgel Gibe dam on the Omo River, which has already flooded huge areas in the southwest; the Koka dam on the Awash River that has flooded in the east; and the Tise Aby dam on the Blue Nile in the north.

The release of water from these dams "may flood some areas," the task force said in a statement released by the information ministry.

In addition to the confirmed deaths, some 250 people are missing and 73,000 are affected, many of them left homeless by the raging waters that have killed thousands of valuable livestock and flooded huge tracts of farmland.

Officials said they had relocated at least 15,000 people to safer areas in view of the increasing threat of fresh flooding across the country, according to state television.

Some 13,000 people in the northern region and another 2,000 in the south had been relocated for fear of further flooding and landslides.

Overwhelmed authorities have appealed for international aid, and US soldiers began relief work on Saturday in the town of Dire Dawa, about 500 kilometers (300 miles) east of Addis Ababa, which was hit by floods on August 6.

The 35 Djibouti-based US naval engineers were setting up 52 large tents to house many of 6,000 people displaced by the waters, which killed 256, and erecting sanitation facilities amid growing fears of the spread of water-borne diseases.

"I am very impressed with what the Ethiopians and the others are doing to help the displaced. I am glad that we are part of this operation," Richard Hunt, head of the Djibouti-based Combined Joint Task Force-Horn of Africa, told AFP by phone.

With poor weather continuing to hamper relief efforts, particularly in the southwest Omo River valley where 364 drowned last week and up to 8,000 remain marooned in 14 inundated villages, officials feared a rise in the death toll.

"The rain in the highlands has continued, and the river waters are showing no signs of decreasing," said Major Solomon Gebere Michael, commander of army relief operations in the Southern Nationalities, Nations and People's state.

"It is hurting the search and rescue mission," he told AFP by phone from Amorate, some 800 kilometers (500 miles) south of Addis Ababa.

Military helicopters dangling special forces troops from ropes and ladders continued to fly over affected areas, dropping food and water and attempting where possible to pluck survivors from roofs and tree tops, Solomon said.

At the same time, he said rescue teams in boats had begun to face difficulties due to powerful currents and obstacles in newly created vast marsh areas in the Omo basin.

Meteorologists have warned that six areas in the north, west and south of the country will likely face further flood threats from the downpours that are expected to continue until the end of the June-to-September rainy season.

Ethiopia has repeatedly suffered heavy floods and droughts in recent years, devastating agriculture that provides a livelihood for the majority of the 70 million people living in the Horn of Africa nation.