The International Trade Secretary said, on the eve of a visit to the country, that the new funding would help firms take advantage of the UK’s exit from the EU and the “once in a lifetime opportunity” it would bring to business.
He will also visit the east African nation of Mozambique during his trip designed to strengthen trade relations between Britain and the continent.
The UK did £30billion-worth of trade with Africa last year.
Under the plans, support for trade with South Africa will be doubled to about £3.5billion.
Dr Fox said: “As we leave the EU, it is a once in a lifetime opportunity to build a more open and outward looking Britain and forge independent trading arrangements with growing economies around the world.”
The news comes as the CEO of Burberry has hailed ‘enormous’ potential for trade post-Brexit, insisting ‘British resonates globally’.
Christopher Bailey said the decision to leave the European Union presented “potential for growth” and said international trade was the “fabric of this country”.
Speaking to BBC Radio 4’s Today programme from this year’s London fashion week, the designer played down concerns aired by those who backed Remain last year.
He said: “I think it’s enormous, I think it’s a much smaller world today than it’s ever been in terms of being able to trade.
“We as a business have always traded globally and Thomas Burberry, our founder 160 years ago was already trading globally, the fabric of this company has always been about trading overseas as well as here in the UK.
“The possibilities and the potential for growth, both locally here in the UK and overseas, is enormous.
“And just talking from a very selfish point of view, I think the Britishness resonates globally.”