Thandi Modise, deputy secretary-general of the African National Congress, said her country wanted to see a recovery in Zimbabwe that would allow millions of Zimbabweans who have fled economic meltdown in their country to return home.
She said the more than three million Zimbabweans who had crossed the border were placing a huge strain on South Africa’s healthcare, education and housing resources.
Zimbabwean President Robert Mugabe and his longtime rival Prime Minister Morgan Tsvangirai of the Movement for Democratic Change (MDC) formed a unity government in February, but are still wrangling over a power-sharing agreement that could pave the way for reforms.
Years of economic crisis, characterised by record rates of hyperinflation, forced millions of Zimbabweans to seek work in South Africa, where there were bloody clashes last year between economic migrants and South Africans worried about their jobs.
South African President Jacob Zuma went to Zimbabwe last week to press Mugabe and Tsvangirai to resolve their differences so that foreign economic aid can begin to flow.
As mediator, Zuma has been expected to adopt a more robust line with the feuding Zimbabwean leaders than his predecessor, Thabo Mbeki, who advocated quiet diplomacy but was criticised for being too close to Mugabe.
Modise said South Africa wanted negotiations between Mugabe and the MDC to pick up pace.
South Africa and southern Africa as a whole wants to see a Zimbabwe that is beginning to work and to put its citizens first, she said.
"And that is why we are encouraging the talks between President Mugabe and the MDC to be more positive, to be faster, because all of us need to see our countries working as well as they can do," she told Reuters in an interview on Wednesday during a visit to London.
"It is important to South Africa and to the ANC in particular to begin to see a situation in Zimbabwe which will enable Zimbabweans in South Africa and elsewhere in the world to come back to Zimbabwe to rebuild their country," she said.
"I think there are more than three million Zimbabweans in South Africa. We would want to see a situation back in Zimbabwe which will enable these people to go back home," she said.
South Africa could not repatriate the Zimbabweans and "you cannot turn your back on your neighbours when they are in need".
"So President Zuma will do what he can to mediate to ensure that things are working in Zimbabwe," Modise said.
Tsvangirai said on Tuesday he wanted next week’s summit of regional leaders to push Mugabe to fulfil the power-sharing agreement and to speed up reforms.
Tsvangirai said the Southern African Development Community, meeting in the Democratic Republic of Congo on September 7 should remove obstacles to the unity pact.
Modise was in London to launch the ANC’s first foreign branch since the party came to power in 1994.