Lack of drainage and poor construction means thousands every year lose their homes. But this year, officials say Sudan was hit by the worst floods in living memory, with rivers reaching critical levels in many states.

"Four weeks after torrential rains started to devastate many parts of the Sudan, the United Nations and partners, in support of the Government, have so far assisted up to half a million people affected by the floods," the UN report said.

"Well over 30,000 houses were fully destroyed. At least 365,000 people have already been directly affected, including a reported 64 dead and 335 injured," it added.

David Gressly, acting UN Resident and Humanitarian Coordinator in the country, said UN and aid agencies and the Sudanese government reacted swiftly, preventing disaster.

"(But) If current flooding patterns continue unabated, the situation will deteriorate considerably", he added.

Officials provided blankets, plastic sheeting, water storage and cooking materials to 200,000 people, as well as water purification products and soap to 500,000 people to prevent disease.

"Despite these preventive measures, 637 cases of suspected acute watery diarrhoea were reported in the states of Gedaref and Kassala in the country's east, leading to 39 known deaths," it said.