A general view shows water flowing from the dam that burst its walls, overrunning nearby homes, in Solai town near Nakuru, Kenya. Picture: Reuters/Thomas Mukoya

Nairobi - Kenya's chief prosecutor on Friday ordered police to investigate a dam-burst on a commercial farm in the Rift Valley that killed dozens of people as a wall of water tore down a hillside, obliterating everything in its path.

At least 44 people were killed when the reservoir, used to store water for the farming of roses for export to Europe, burst its banks on Wednesday night after heavy rains. Another 40 people have been reported missing.

The public prosecutor's office said on Twitter the police chief had been ordered "to carry out thorough investigations to establish cause and culpability if any" behind the disaster and file a report within two weeks.

The Daily Nation newspaper quoted government officials as saying the dam and others on the 3 500-acre Solai farm, 190 km (120 miles) northwest of Nairobi, had not been cleared by government engineers.

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Villagers had complained when the dams were built, accusing the farm-owner of depriving them of access to river water, the paper reported.

Vinoj Kumar, general manager of the farm, blamed the disaster on heavy rainfall in a forest above the dam. He declined to comment on the Daily Nation allegations, saying he was too busy to talk.

Kenya's cut-flower sector, in the fertile Rift Valley, has grown dramatically in the last decade to become one of the biggest foreign exchange earners in East Africa's largest economy and a major source of employment.

After a severe drought last year, East Africa has been hit by two months of heavy rain that has affected nearly a million people in Kenya, Somalia, Ethiopia and Uganda. Bridges have been swept away and roads turned into rivers of mud.

More than 150 people have been killed and 300 000 displaced in Kenya, where roads, bridges and crops have been swept away, causing millions of dollars of damage.

"We all breathed a sigh of relief when the rainy season started strong in early March," said Lane Bunkers of Catholic Relief Services in Kenya.

"But now - two months later - we are seeing the consequences of the drought-ravaged land's inability to absorb all the rain due to its degraded state."