Zimbabwe's ruling party and the opposition will begin negotiations on Tuesday on a power-sharing deal that could end a political crisis, an official for the opposition Movement for Democratic Change said.

The talks will open a day after President Robert Mugabe and opposition leader Morgan Tsvangirai signed a deal that committed the ruling ZANU-PF and two factions of the MDC to two weeks of negotiations with South African mediators.

"There was convergence among all the parties that the dialogue had to start as soon as the MOU (Memorandum of Understanding) was done, hence the resumption of that process today," the MDC official said on condition of anonymity.

The official said MDC representatives would fly to South Africa for the talks.

Mugabe's government and the opposition had been deadlocked over talks since the Zimbabwean leader was re-elected on June 27 in a poll boycotted by Tsvangirai because of violence against his supporters. Mugabe blames the opposition for the violence.

The establishment of a government of national unity will be the main issue in the talks, although both sides differ on who should lead it and how long it should stay in power.

The African Union and the Southern African Development Community (SADC), both concerned by a crisis that has flooded neighbouring states with millions of refugees, have pushed for a power-sharing deal.

Prospects for talks between Zimbabwe's rivals appeared to change late last week when Mbeki agreed to expand the mediation process to include the African Union, United Nations and other officials from the SADC as a "reference group".

Tsvangirai had previously refused to enter formal talks unless government militias stopped violence he says has killed 120 of his supporters. He also wanted Mugabe to recognise his victory in the first round of the presidential poll on March 29.

Mugabe, 84, has described the MDC as a puppet of the West, vowing never to allow it to take power and demanding that it recognise his landslide victory last month.

Zimbabwe's economic collapse under Mugabe's 28-year rule has plunged the once prosperous country into inflation of at least 2 million percent as well as crippling food and fuel shortages.