Cape Town — South Africa's President Thabo Mbeki headed for Harare again on Monday to try to nudge Zimbabwe's deadlocked political parties into a powersharing settlement.

The visit follows in the wake of a reported call by Morgan Tsvangirai, leader of the Movement for Democratic Change (MDC), for a fresh presidential election if the parties cannot agree.

Parliamentary and presidential elections in March gave the MDC a slight edge over President Robert Mugabe's Zanu-PF, and the support it needed to take the speakership of Parliament, but not the presidency.

A presidential run-off vote was organised for June but Tsvangirai pulled out of the race after violence against his supporters. The resulting election of Mugabe has little credibility in Africa or elsewhere.

Talks facilitated by Mbeki, appointed to the role by the Southern African Development Community, have since failed to bridge differences between the MDC and Zanu-PF.

Both have agreed to join a unity government, with Mugabe as president and Tsvangirai as prime minister, but the MDC says the deal on offer does not give Tsvangirai sufficient powers.

Agence France-Presse reports that Tsvangirai told a party rally in Gweru: "If there are continued problems over the presidency, then we go for national elections supervised by the international community."

He said Mugabe should be head of state and he head of government, and added: "If he does not accept that, let it be. We have time on our hands and we have the people on our side... We would rather have no deal than a bad deal."

Announcing Mbeki's visit to Harare, South African foreign ministry spokesman Ronnie Mamoepa said the president would meet leaders of the Zimbabwean parties and would be supported by members of his facilitation team, who include cabinet minister Sydney Mufamadi and the top civil servant in his office, Frank Chikane.