"We have about 73,000 houses completely destroyed and 29,000 partially destroyed," said Hamadallah Adam Ali, head of Sudan's civil defence authority.

He said 150 people had been killed and 302 injured by the flooding, with 42,000 livestock lost.

Ali said that 1,748 public buildings had been damaged, estimating the total losses at US$300 million.

"These are the worst floods in Sudan. There has been no flooding like this in years," he said.

Many roads and bridges have been cut off and the World Food Programme said it was airlifting food and relief supplies to flood victims in remote areas of southern Sudan.

Ali said Sudan needed help to compensate all the victims. "The United Nations has to help us rehabilitate," he said.

This week the world body said only US$1 million of an appeal for US$20 million had been received from donors.

Sudan's multiple conflicts in the south, east and western Darfur regions have drained around US$1 billion a year of donor cash for humanitarian and reconstruction efforts.

On top of that, a new joint UN-African Union peacekeeping force for Darfur will cost more than US$2 billion a year and a separate UN peacekeeping force in the south cost more than US$1 billion in its first year.