In a bid to overcome reliance on food imports, countries in Asia and the Gulf have been at the forefront of farmland purchases in the world's poorest continent, where millions survive on subsistence farming.

Cereals production could fall by 50 percent in parts of southern Africa in the long term due to climate change, causing increased hunger and poverty, a researcher told an agriculture conference on Wednesday.

South Africa is the largest carbon emitter on the continent, mainly due to its reliance on coal to produce most of its electricity.

South African farmers have been offered 10 million hectares of farm land to grow maize, soya beans as well as poultry and dairy farming in the Republic of Congo, South Africa's main farmers union said on Wednesday.