In his opening speech, Mwanawasa said he had called the summit because of the failure of Zimbabwean officials to publish the results of March 29 presidential election.
Independent tallies indicate Mugabe lost, but garnered enough votes to force a runoff. Opposition leader Morgan Tsvangirai says he won outright and has traveled the region asking neighboring leaders to push for Mugabe to step down.
Tsvangirai was invited to address the summit, an unprecedented move that further alienated Mugabe. But there appeared little likelihood the leaders would call for Mugabe's resignation.
Officials at the conference indicated they would focus on the delayed election results and not Mugabe's rule.
US Ambassador Carmen Martinez, among more than a dozen diplomats on the sidelines of the summit, said the United States was looking for "at least one step forward."
Mbeki, the chief mediator on Zimbabwe, urged patience after he flew to Harare to meet with Mugabe ahead of the summit. "Everybody is waiting for the Zimbabwe Electoral Commission to announce the results," he said.
The release of Zimbabwe's election results ceased after results from legislative races held the same day as the presidential vote showed Mugabe's party lost control of parliament for the first time. The election commission has released no results from the presidential race, saying it was still verifying the votes.
Meanwhile, Mugabe has dug in his heels, banning political rallies amid opposition charges he was orchestrating a wave of violence to intimidate opponents. He sent three hard-line ministers from his outgoing Cabinet to represent him at the summit.
Tendai Biti, secretary general of Tsvangirai's party, said the military had taken control of Zimbabwe and urged the summit leaders to "speak strongly and decisively against the dictatorship."
"Our people are suffering, our people are being brutalized, our people are being traumatized," he said in Lusaka.
International pressure has grown with the United States, Britain, and the United Nations issuing daily statements demanding the results. Regional human rights and church organizations have made similar demands.
British Prime Minister Gordon Brown has said the world's patience with Zimbabwe's regime was "wearing thin." Mugabe has dismissed Brown's criticism, calling the British leader a "little tiny dot" on the world stage.
Mugabe's allies said yesterday's summit was part of a Western plot to overthrow him because of his land reform program, which was touted as an effort to redistribute the wide swathes of fertile land owned by the tiny white community to poor blacks.
READER COMMENTS »
View reader comments » Comment on this story »