South African President Thabo Mbeki will visit Zimbabwe on Wednesday for talks with his counterpart Robert Mugabe ahead of next week's presidential election run-off, Zimbabwean state media reported.

Citing reliable sources, the state-owned Herald newspaper said Mbeki would meet Mugabe in Zimbabwe's second city of Bulawayo.

"South African President Thabo Mbeki is expected to meet President Robert Mugabe in Bulawayo today to discuss the forthcoming presidential election run-off and the campaigns," the newspaper said.

"President Mugabe will travel to Bulawayo for the meeting after addressing rallies in Gwanda and Beitbridge."

But Ronnie Mamoepa, a spokesman for South Africa's Department of Foreign Affairs, said he was unaware of any visit by Mbeki.

Mbeki has been tasked by the regional SADC grouping of southern African countries to mediate between Zimbabwe's ruling ZANU-PF party and the main opposition Movement for Democratic Change (MDC). Critics have said the mediation has been largely ineffectual.

MDC spokesman Nelson Chamisa said the party was unaware of any visit by Mbeki and Mbeki's spokesman Mukoni Ratshitanga told Reuters he would be speaking to the South African leader at 8:00 a.m. British time.

The opposition accuses Mugabe of a campaign of violence ahead of the run-off between Mugabe and MDC leader Morgan Tsvangirai. Mugabe blames his opponents.