South Africa's President Thabo Mbeki is flying to Harare to revive Zimbabwe's deadlocked power-sharing talks. BBC Southern Africa correspondent Jonah Fisher says this may be the last chance for Mr Mbeki's mediation. Both Robert Mugabe and opposition leader Morgan Tsvangirai claim to have won this year's elections, marred by widespread violence. Since South Africa-brokered crisis talks broke down last month, both sides have hardened their positions. Mr Mugabe has said he is ready to form a government alone, while Mr Tsvangirai over the weekend said there should be new elections if a deal is not reached. South African Ministry of Foreign Affairs spokesman Ronnie Mamoepa said Mr Mbeki would meet both men, as well as Arthur Mutambara, the leader of a smaller opposition faction. 'Surrender powers' Before talks broke down, the two rivals had agreed that Mr Tsvangirai would be named prime minister while Mr Mugabe remained president, but they could not agree on how to share powers. The MDC wanted Mr Mugabe to become a ceremonial president, while the ruling Zanu-PF party insisted he retain control of the security forces and the powers to appoint and dismiss ministers. "The issue that we are facing here is that Mugabe must accept to surrender some of his powers for the power-sharing arrangement to work," Mr Tsvangirai told a Movement for Democratic Change (MDC) rally in Gweru, in central Zimbabwe on Sunday. "We would rather have no deal than a bad deal," Mr Tsvangirai said. He also said he would not bow to pressure from Mr Mbeki, who has been acting as a mediator in the crisis. Mr Mugabe said on Thursday that the opposition MDC had one week to agree a power-sharing deal, or he would form his own government. He says he is tired of waiting for the opposition to sign a draft deal and he will push ahead alone if necessary. Our correspondent says a new government dominated by Mr Mugabe's Zanu-PF would continue to face all the same problems - shortages of food, fuel and hyperinflation. Western countries have made it clear they will only lift sanctions and assist in reconstruction if the opposition is given real power. The MDC leader gained more votes than Mr Mugabe in March elections but official results show he did not pass the 50% threshold for outright victory. Mr Tsvangirai pulled out of the June run-off, saying some 200 of his supporters had been killed and 200,000 forced from their homes in a campaign of violence led by the army and supporters of the ruling Zanu-PF. Zanu-PF has denied the claims and accused the MDC of both exaggerating the scale of the violence and being responsible for it. Source: BBC