Johannesburg  - South African President Thabo Mbeki was expected in Zimbabwe Friday for talks with President Robert Mugabe over a month of spiralling post-election violence and a proposed presidential runoff.

Mbeki's spokesman confirmed the visit to Business Day newspaper.

Mbeki is under pressure to take a tougher stance with the 84-year- old leader, who is attempting to cling onto power despite placing second in the March elections, than on his last visit to Zimbabwe, when he declared that he saw no evidence of a "crisis."

Those remarks, which follow years of Mbeki's tiptoeing around the authoritarian Mugabe, drew sharp criticism within South Africa and abroad.

Zimbabwe's opposition Movement for Democratic Change (MDC), which defeated Mugabe's Zanu-PF in the parliamentary elections and whose leader Morgan Tsvangirai took more votes for president than Mugabe, have called several times for Mbeki to withdraw as mediator.

International outrage over mounting casualties in post-election attacks by mainly Zanu-PF youth militia on opposition supporters have forced Mbeki to scale up his intervention.

The MDC claims 30 of its supporters have been killed and scores injured in the attacks in mainly rural areas. Isolated incidents of retaliatory violence by MDC supporters against Zanu-PF members have also been reported.

"This violence and intimidation needs to stop," a spokesman for the White House National Security Council said Thursday.

United Nations Secretary General Ban Ki-moon this week also expressed alarm over the violence and said there could be no free and fair run-off election in a climate of fear.

A second round of voting for president was called for after Tsvangirai failed to win an outright majority of more than 50 per cent at the first round, taking 47.9 per cent to Mugabe's 43.2 per cent in official results.

A high-level South African delegation, led by Local Government Minister Sydney Mumafadi, travelled to South Africa earlier this week for talks with all sides to the dispute and to discuss conditions for a run-off.

The MDC has yet to signal whether it would contest a run-off, while hinting it would if the violence abated and international observers were in place to ensure the vote was free and fair.

Mugabe's government barred election observers from most Western countries from the March elections.

The state-controlled Zimbabwe Electoral Commission has yet to give a date for the run-off, while telling an African election observer mission it would certainly be "within the next 12 months." (dpa)