HARARE - South African President Thabo Mbeki flew into Harare on Monday to meet Zimbabwe's rival parties, amid growing doubts over his chances of securing a power-sharing deal to end the political crisis.

Opposition leader Morgan Tsvangirai said on Sunday he would rather quit talks than sign a bad deal and challenged President Robert Mugabe to hold a new election. Mugabe had threatened to form a government alone if Tsvangirai did not sign last week.

The post-election talks are deadlocked over how to share executive power between Mugabe and Tsvangirai, putting off any chance of rescuing Zimbabwe from its economic collapse.

South African Ministry of Foreign Affairs spokesman Ronnie Mamoepa said Mbeki -- mandated by the region to mediate an end to the crisis -- would meet the leaders of Zimbabwe's negotiating parties.

Mbeki was met at Harare International Airport by Mugabe and the country's security chiefs before being taken to the city hotel where talks were to begin later in the day.

Tsvangirai beat Mugabe in a March 29 election but fell short of enough votes to avoid a June run-off, which was won by Mugabe unopposed after Tsvangirai pulled out, citing violence and intimidation against his supporters.

Mbeki has come under repeated fire for not being tough enough with Mugabe.

Other southern African leaders have taken a harder line against Mugabe, but he has refused to budge, and Tsvangirai's Movement for Democratic Change (MDC) has made it clear it has little faith in Mbeki as a mediator.

NO CHANGE

Tsvangirai told a rally on Sunday marking the party's ninth anniversary that he would not change his position in the power-sharing talks if pressured by Mbeki.

In a commentary in Monday's edition of the government-run Herald newspaper, its political and features editor Mabasa Sasa again accused Tsvangirai of refusing to sign a final deal on orders from Western powers opposed to Mugabe.

"The short history of the opposition is littered with evidence of a cancerous connection with Britain and other Western countries," he said, urging Mugabe to appoint a new cabinet to tackle Zimbabwe's worsening economy.

A breakaway faction of Zimbabwe's opposition MDC said on Monday it will remain independent and not work with Mugabe's ZANU-PF if no power-sharing deal was reached with Tsvangirai.

The breakaway faction headed by Arthur Mutambara said in a statement that its leadership had decided that any agreement would have to be a three-way deal including Tsvangirai's main opposition MDC.

Mugabe's victory in the election run-off was condemned around the world and drew toughened sanctions from Western countries whose support is vital for reviving Zimbabwe's ruined economy.

Tsvangirai told the rally an agreement was out of the question unless Mugabe, in power since independence from Britain in 1980, was prepared to compromise.