“As prime minister of a trading nation whose success depends on global markets, I want to see strong African economies that British companies can do business with,” she said.

I want to create a new partnership between the UK and our friends in Africa built around shared prosperity and shared security.”

May is facing pressure at home from so-called Remainers sceptical of her ability to forge trade deals once Britain severs ties with the EU, as well as from Brexiteers fearful she will not deliver a complete break.

“As we prepare to leave the European Union, now is the time for the UK to deepen and strengthen its global partnerships,” she said in a statement as she arrived in South Africa.

Former foreign minister Boris Johnson, whose July departure from the cabinet brought May’s government to the brink, said in his resignation speech that May’s current Brexit policy would hamper London’s ability to strike independent trade deals. But May said Britain was well placed and had many companies ready to invest in Africa.