Torrential rains that have battered Africa threaten to give rise to a grave humanitarian situation, the Untied Nations Office for the Coordination of Humanitarian Affairs warned in a report.

So far, at least 270 people have died in devastating floods from the continent's east to west coast, and around one million have been affected. As well as wrecking farmland and buildings and leaving hundreds of thousands homeless, the floods have made populations vulnerable to the spread of cholera, dysentery, and meningitis.

The flooding began in mid-June and meteorologists expect another heavy bout of torrential rain in September 18-24. The rains have been the most severe to strike the region in 30 years.

Sub-Saharan Africa has been the worst-hit. The highest casualties have been in Sudan, where 64 people have been drowned in floods, and water-borne cholera has taken 49 lives, and Ghana, where flood waters have covered most arable land, and killed 32 people, the UN report said.

In Sudan, 500,000 people have been made homeless, and another 230,000 in Ghana. Nigeria, Togo, Rwanda, Niger, Somalia, Morocco, Mauritania, Ethiopia, and Uganda have also been hard-hit.

Some African states have declared a state of emergency and called for international assistance.

International humanitarian organizations including the International Health Organization (IHO), World Food Organization (WFO), and the International Committee of the Red Cross (ICRC) have begun providing aid to the victims.

Some African officials say the level of destruction caused by the floods is due to deforestation, which has removed a vital safeguard against landslides, and reduced the ground's capacity to absorb floodwater.