Zimbabwe's protracted negotiations on the formation of a power-sharing government moved to Swaziland on Monday, where key leaders of the  Southern African Development Community (SADC) were scheduled to try to  broker agreement on a cabinet.

In a development which introduced a new dynamic into talks, the South African government announced that newly-inaugurated President Kgalema Motlanthe would join a meeting of  the SADC security committee known as the "Organ on Politics, Defence and  Security."

The organ comprises a "troika" of Angola, Swaziland and Tanzania and is  currently headed by King Mswati III of Swaziland.

Motlanthe represents forces in South Africa's African National Congress  perceived by Zimbabwe's Zanu-PF party to be less sympathetic to  President Robert Mugabe than the SADC facilitator of the power-sharing  talks, former President Thabo Mbeki.

Zanu-PF showed signs of nervousness ahead of the Swaziland talks, with  top negotiator Patrick Chinamasa telling the Sunday Mail, a  government-supporting newspaper: "They (the troika) can't impose  anything on us, especially on such a small matter as the allocation of  ministries."

Four days of talks in Harare last week failed to produce an agreement on the composition of a cabinet.

The Sunday Mail backed up Chinamasa's statement with quotes attributed  to an unnamed "top constitutional expert," who attacked the Movement for  Democratic Change of Prime Minister-designate Morgan Tsvangirai and  reiterated that SADC and the African Union, as guarantors of the  power-sharing deal which Zimbabwe's political parties signed in  September, could "only give advice."

"The AU and SADC are supposed to guarantee the agreement and not make it  work. They don't guarantee its success. Zimbabweans are masters of their  own destiny... The guarantors do not have a veto," the unnamed source said.

Mugabe was reported to have arrived with Chinamasa and other members of his delegation in Swaziland on Sunday night.