Southern African leaders opened a regional summit on Zimbabwe in South Africa on Sunday, hoping to break a deadlock over the allocation of cabinet posts which has prevented formation of a power-sharing government.
The 15-nation Southern African Development Community (SADC) meeting is trying to end the impasse between President Robert Mugabe and opposition leader Morgan Tsvangirai and put into effect a power-sharing deal reached in September.
South African President Kgalema Motlanthe said in opening remarks that the agreement signed by Zimbabwe's political rivals was the only hope for the country to revive its collapsed economy.
"The historical agreement signed on the 15th of September is the only vehicle to help Zimbabweans (with) their economic challenges," Motlanthe told the summit.
Mugabe and Tsvangirai were both attending the summit.
Motlanthe said there was some disappointment that the Zimbabwean parties had not agreed how to allocate cabinet posts.
"We hope the parties will show political maturity by putting the interest of the people of Zimbabwe first," he said.
Past meetings of regional heads of state have failed to produce a breakthrough and there were new signs that the parties may face another round of difficult negotiations.
Tsvangirai's MDC said last week that Mugabe's ZANU-PF party had put a "full stop" to negotiations on forming a government by carrying out what it said was widespread violence.
Zimbabwean state media reported on Sunday that Mugabe's government would not change its stance on key positions in a power-sharing cabinet and the opposition should accept joint control of the interior ministry.
Justice Minister Patrick Chinamasa told the state-run Sunday Mail the deadlock would end only if Tsvangirai agreed to joint control of the ministry, which oversees the police.
"The proposals are on the table and the ball is in Tsvangirai's court," Chinamasa said.
"We want to make it clear that this proposal, which ZANU-PF accepted as a compromise, was originated by Tsvangirai himself."
Tsvangirai, who would become prime minister under the power-sharing deal, has accused ZANU-PF of trying to seize the lion's share of important ministries and relegating the MDC to the role of junior partner.
South Africa's government has said it will take a tough stand at the summit - a sharp change from the style of former President Thabo Mbeki, the official mediator whose policy of quiet diplomacy was criticised as ineffective.
It is not clear what practical steps the SADC could take to force an agreement on the two rivals.
Zimbabwe's economic crisis has forced millions of its citizens to flee the country, an estimated three million of them moving to neighbouring South Africa alone.
Ties between Zimbabwe and neighbouring Botswana have also become strained after Botswanan President Seretse Khama Ian Khama said a new election was the only solution to the crisis.
Establishing a unity government is seen as critical to reversing economic meltdown in Zimbabwe, where inflation is officially 231 million percent. Even under government price controls, the cost of bread is doubling every week.
Zimbabweans are struggling to survive amid widespread shortages of meat, milk and other basic commodities as a result of the collapse of the agricultural sector. The country is dependent on food handouts and malnutrition is on the rise.