Leading article: Jacob Zuma's economic tightrope

Jacob Zuma will arrive in Britain this week with two priorities. He will be doing all he can to strengthen trade links and he will be pressing for an end to the sanctions targeted on the ruling elite in his neighbour Zimbabwe. Gordon Brown should embrace the former but give little heed to overtures to slacken international disapproval of the Mugabe regime.

Zimbabwe is a good drum for Mr Zuma to beat, for it will draw attention away from the deepening divisions among the supporters of his government and from the latest embarrassing row about his sex life. On the political front his supporters on the left this week condemned the Zuma government budget speech, saying it was not doing enough to deliver jobs and homes for the poor. Mr Zuma responded with sympathetic noises, but also made noises designed to reassure international businessmen that economic policy will not shift and that their investments were safe.

How long he can walk this social and economic tightrope is unclear. But on the personal front he stumbled this week when he had to issue a personal apology to the nation after it became known that the polygamous president has a four-month-old illegitimate child by the daughter of the president of South Africa's World Cup organising committee. Mr Zuma's chequered sex life hardly sets a good example in a country which has more Aids cases than anywhere else in the world.

On trade the interests of London and Pretoria coincide. Britain was South Africa's fourth largest export partner in 2008 and its biggest source of tourists. And Downing Street will be interested in Mr Zuma's idea that the Commonwealth has a role to play in reforming international bodies like the United Nations, the International Monetary Fund and the World Bank to make them more sensitive to the needs of developing countries.

But there is little strength to Mr Zuma's argument that it is time to end sanctions on the Mugabe elite in order to improve the working of Zimbabwe's power-sharing government. That is faltering because Mr Mugabe does his cynical best to undermine it at every turn. Before he came to power Mr Zuma called for South Africa to take a much harder unilateral line. Gordon Brown should gently remind him of that.