Namibia says it is sending in helicopters and hundreds of soldiers to battle a fire that has ravaged a third of a key nature reserve.

Etosha National Park is one of southern Africa's top tourist attractions, known for its vast salt pan that can be seen from space. It is also home to critically endangered black rhinos.

The country's environment ministry believes the fire broke out on Monday at a charcoal production outside the park's borders.

Almost a week on, it has spread into the park killing at least nine antelope and destroying wildlife habitats, as well as grazing pasture in the Omusati and Oshana regions bordering Angola.