Gordon Brown says he is not in South Africa to "pitch for a job" at the International Monetary Fund.
There is mounting speculation the former British Prime Minister wants to become the next IMF chief -- following the resignation of Dominique Strauss-Kahn.
Brown, who is due to make a speech on aid in South Africa, said: "Any candidate to head the IMF needs to be appointed on merit".
Strauss-Kahn denies charges of trying to rape a hotel maid in the U.S. He resigned on Thursday saying he wanted to devote his attention to "proving my innocence".
There have been reports Brown, who was U.K. chancellor of the exchequer for 10 years before becoming prime minister in 2007, is mounting a bid for the top job at the IMF.
He is in South Africa to launch a report warning of an "education emergency" in the developing world -- and has called on richer countries to donate billions of pounds a year to a new Global Education Fund. One source reported the speech would help stake his claim to be the next IMF chief.
Brown, who remained an MP after the Labour Party lost power in last year's general election, took on an advisory role at the World Economic Forum last month.
His global profile rose during efforts to alleviate the effects of the financial crisis while in Downing Street.
But current Prime Minister David Cameron appeared to kill off Brown's chances of succeeding Strauss-Kahn in April, when he said the former PM "might not be the best person" for the job.
Backing from a candidate's national government is seen as prerequisite for selection -- the final decision is made by the IMF's executive board.
Acting IMF chief John Lipsky said on Friday that French Finance Minister Christine Lagarde would be an "excellent choice" to replace Strauss-Kahn.
