Festus Mogae, Botswana’s former president who made the fight against HIV and AIDS a national priority during his tenure from 1998 to 2008, has died at the age of 86, the government said on Friday. No cause of death was given.

Botswana President Duma Boko said that under Mogae’s leadership, the country earned international respect for principled, sound economic management and a commitment to democracy. He said the country would observe three days of national mourning in honour of its former head of state.

Botswana, a sparsely populated and arid country in southern Africa, is the world’s largest producer of diamonds by value and the second largest by volume, behind Russia. Diamonds account for around 80 per cent of Botswana’s exports and a quarter of its gross domestic product, according to the International Monetary Fund.