KAMPALA - Thousands of Ugandans face severe food shortages, malnutrition and cholera due to flooding that has forced them from their homes, aid agencies said on Tuesday.

In separate statements, the U.N. World Food Programme and British charity Oxfam said 300,000 Ugandans had been affected by some of the worst floods in living memory. A fifth of them were forced to flee their homes.

Uganda has been one of the countries worst hit by torrential rains and flash floods that have swept over east and west Africa washing away villages, food crops and animals.

Conservative estimates put the total number of people killed -- from Ethiopia in the east to Senegal in the west -- at 200. Aid agencies say 1 million people are affected.

In Uganda, 20 people have died and with more rain expected aid workers fear the toll could climb.

"We are quickly running out of food ... before long, thousands of flood-hit families will have nothing else to eat," WFP Executive Director Josette Sheeran said.

"It can take just days for ... acute malnutrition to claim the life of a child."

WFP said it needs about $25 million for emergency food aid and vehicles.

Oxfam said the risk of a cholera epidemic was also serious because of reduced access to clean water".

Hundreds joined Ugandan President Yoweri Museveni on a walk through Kampala on Friday to raise money for flood victims.