A last ditch effort by southern Africa leaders to broker a deal between Zimbabwe's political leaders by the end of a regional summit, has faltered on one significant element.  VOA's Delia Robertson reports from our southern Africa bureau in Johannesburg talks will resume at an unspecified date and place.

Angola's Foreign Minister Joao Miranda says that a meeting with the so-called "Organ on Peace and Security" of the Southern Africa Development Community brought Zimbabwean leaders closer together, but did not entirely close the gap between them.

Zimbabwe's President Robert Mugabe at the closing ceremony of the 28th Southern African Development Community summit in Johannesburg, 17 Aug 2008

Miranda says that President Robert Mugabe and opposition Movement for Democratic Change majority leader Morgan Tsvangirai could not find accord on the power vested in the positions of president and prime minister.

A senior official in Tsvangirai's party who declined to be identified, has told VOA that his party wants the prime minister's position, likely to be occupied by Tsvangirai, to have sufficient authority to be able to govern.  This includes having the authority to appoint and dismiss cabinet ministers.

He said the party also wants the period of transition of a future government of national unity to be limited to 2.5 years.

Mr Mugabe is expected to retain the position of president and he would also like to have as much authority invested in the position as he can get.  He wants a transitional period of five years.

S. African President Thabo Mbeki comes out of Rainbow Towers hotel in Harare where he was facilitating talks between ZANU-PF and the two MDC formations, 13 Aug 2008

South African President Thabo Mbeki, mandated last year to mediate the talks by SADC, took this opportunity this weekend to escalate the talks to the "Organ" - commonly know in the region as "the troika".  It is headed by three regional heads of state on a rotational basis.  Currently they are the presidents of Angola and Mozambique and the Swazi King.

Mr. Mbeki said, after the talks stumbled, that a deal must be reached by the entire collective of Zimbabweans leaders and be a common product owned by them.  He said anything imposed from outside will not last.

Mr. Mbeki also said that it may be necessary to convene parliament in Zimbabwe while negotiations are continuing to, in his words, "give effect to the will of the people as expressed in the parliamentary elections held on the 29th of March  2008".

Meanwhile, Tendai Biti, Secretary General of the MDC said after the meeting that it is critical that negotiations be concluded soon and that failure is not an option.