Zimbabwe's main opposition party and the ruling Zanu-PF party are reportedly close to reaching a deal on forming a unity government.

Senior Movement for Democratic Change officials and two Zimbabwean cabinet ministers are leading the rival negotiating teams at an undisclosed venue close to the South African capital Pretoria.

Their aim is to end the deadlock over President Robert Mugabe's re-election on June 27 in a poll boycotted by the opposition after their supporters became the target of violence.

Preliminary talks began on Tuesday after South African President Thabo Mbeki secured a framework deal between Mr Mugabe and MDC leader Morgan Tsvangirai.

Mr Mbeki's spokesman Mukoni Ratshitanga said even if negotiators missed a two-week deadline set under the framework agreement, it did not mean the end of talks.

The main aim of the Pretoria talks will be the creation of a government of national unity, but the two sides differ on who should lead it and how long it should stay in power.