MAPUTO (Reuters) - Floods in Mozambique and northern parts of South Africa over the past week have killed at least 20 people and driven nearly 15,000 from their homes, authorities said on Tuesday.

Mozambique's emergency management commission issued a nationwide alert as it prepared for further flooding in central and southern regions and the possible evacuation of tens of thousands.

Heavy rain has hit the capital Maputo hard, submerging cars and swamping streets in the city's low-lying financial district. At least 12 have been killed nationwide in the floods.

In neighbouring South Africa, the Limpopo River overflowed its banks, inundating streets and destroying homes in the northern city of Musina. At least eight people have been killed and the number was expected to rise, local officials said.

There were no immediate estimates of economic damage from Mozambique or South Africa.