Zimbabwe's opposition leader Morgan Tsvangirai has challenged President Robert Mugabe to hold a new election if he is not prepared to share his powers. Mr Tsvangirai said he would withdraw from power-sharing talks if a satisfactory deal could not be reached. Mr Mugabe has said he will form a government without the MDC if they do not agree to a power-sharing deal being mediated by South Africa's president. Mr Mugabe and Mr Tsvangirai both say they won elections earlier this year. "The issue 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. Talks deadlocked At talks mediated by South Africa, the two rivals have agreed that Mr Tsvangirai would be named prime minister while Mr Mugabe remained president, but they cannot agree on how to share powers. The MDC wants Mr Mugabe to become a ceremonial president, while the ruling Zanu-PF party insists he retain control of the security forces and the powers to appoint and dismiss ministers. "We would rather have no deal than a bad deal," Mr Tsvangirai said. He also said he would not bow to pressure from South African President Thabo Mbeki, who has been acting as a mediator in the crisis. Mr Mbeki is due to return to Zimbabwe's capital Harare on Monday to continue the search for a solution to the political impasse. 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 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. Mr Mugabe said on Thursday that the opposition MDC had one week to agree a power-sharing deal, or he will form his own government Source: BBC