At least 21 people have died in Madagascar following almost a week of flooding and landslides from torrential rain, the government says, with some homes being evacuated by the military.

Another 20 people are missing, and thousands more have been displaced, according to the national disaster management office. It now warns there is a risk of "food insecurity and malnutrition" because many rice-growing fields are flooded.

The worst-affected zone is in the north of the country, where some 10,000 homes are flooded.

Madagascar, the world's fourth largest island, is prone to cyclones and tropical storms. The Indian Ocean island is currently at the height of its rainy season.