South Africa's presidency issued an embarrassing correction on Monday to rectify an erroneous reference last month by President Jacob Zuma to Africa being the "largest continent".

The comments were seized upon by Zuma's opponents, who argue that his lack of schooling makes him unfit to lead a sophisticated emerging economy.

It was unclear why the presidency decided to issue the correction after a delay of nearly six weeks.

"Africa is in fact the second biggest continent in terms of population size, and the biggest continent in this regard is Asia. The President regrets the error," the statement said.

Zuma's comments about Africa's size came hours before he fired respected finance minister Nhlanhla Nene in favour a relative unknown, triggering financial turmoil that sent the rand, bonds and stocks plummeting.