Bananas are a staple food for millions across Africa

Food supplies in several African countries are under threat because two diseases are attacking bananas, food scientists have told the BBC.

Crops are being damaged from Angola through to Uganda - including many areas where bananas are a staple food.

Experts are urging farmers to use pesticides or change to a resistant variety of banana where possible.

Scientists have been meeting in Tanzania to decide how to tackle the diseases, which are spread by insects.

'Big danger'

A statement from the Consultative Group on International Agricultural Research (CGIAR) said "drastic and expensive control measures" were needed.

BANANA DISEASES Bunchy top

Ethiopia, Uganda, Rwanda, Kenya, Tanzania, Gabon, DR Congo, Congo Republic, northern Angola and central Malawi Bacterial wilt

Ethiopia, Uganda, Rwanda, western Kenya, north-western Tanzania, North and South Kivu in DR Congo

Source: CGIAR

These include "completely excavating entire banana fields and treating them with pesticides, or burning the plants".

Experts say the two diseases - bunchy top viral disease and bacterial wilt - are both spread by insects and very few varieties of banana have resistance to them.

While bunchy top stunts the growth of plants by causing leaves to sprout from the top, bacterial wilt kills off plants and makes their fruit inedible.

Christopher Chemirehreh, of the Kawanda Agricultural Research Institute in Uganda, said people were particularly vulnerable in the areas where the diseases were found.

"It's a big danger because the affected areas have the banana as their staple crop," he told the BBC's Focus on Africa programme.

"So if they fail to control the bacterial wilt, their incomes are affected and their food is affected, so it's a very big problem."