Eastern DR Congo faces a "humanitarian catastrophe" after being hit by severe flooding affecting about half a million people, the UN World Food Programme said Wednesday.

"Heavier rainfall than usual during the rainy season, prompted by climate change, has forced rivers and lakes to overflow, swallowing towns, villages and roads on the shores," the WFP said in a report citing "chaos" in  South Kivu and Tanganyika provinces.

Worst-affected are Haut-Lomami and Tanganyika provinces, which border the lake of the same name as well as neighbouring Burundi, Tanzania and Zambia.

"All around Lake Tanganyika, and areas upstream of the Congo River basin, people have lost their homes, their fields and livelihoods," the WFP reported,  estimating 471,000 people were affected with 451,000 hectares (1.1 million acres) flooded, including 21,000 hectares of cropland.

"People in flooded areas need food, shelter, clean drinking water, health and sanitation support, as well as support to restart their livelihoods.

"However, WFP has very limited resources to respond to the flooding crisis due to current funding levels and the food assistance pipeline situation."

The UN body voiced concern at the effect on health service provisions as sickness hit affected areas of the Democratic Republic of Congo (DRC).

"With towns and villages swallowed in the lakes and rivers, diseases are rife. Latrines have overflowed into the water that surrounds people’s homes and sanitation is poor.

"People are forced to wade through and wash their clothes and cooking implements in cholera-riddled water," said the report, warning of "a whole host of animal-borne diseases."

Locals were reporting seeing hippos, crocodiles and snakes in flooded inhabited areas, risking fatal attacks, especially on children and livestock.

Amid lost harvests, "people are struggling to feed their families which is leading to more people arriving in health care facilities with symptoms related to months of poor food intake. Especially children are at risk of developing malnutrition."

Flooding has hit vast swathes of Africa in recent weeks, which have notably claimed 257 lives in Kenya, according to a latest toll Wednesday.