Southern African leaders concluded their summit Sunday, but not their talks on Zimbabwe's protracted crisis.

The summit host, South African President Thabo Mbeki, said the Southern African Development Community's key committee on security and politics had been discussing Zimbabwe since Friday, and after formal closing ceremonies "will convene again just to deal ... with the situation of Zimbabwe."

Mbeki has been mediating power-sharing talks between Zimbabwean President Robert Mugabe and the opposition, navigating a bitter rivalry that has defied quick solutions. Zimbabwean opposition leader Morgan Tsvangirai, who attended Sunday's summit closing, said negotiations were continuing.

"The issue has not been finalized," Tsvangirai said.

In a speech Friday to SADC leaders, Tsvangirai said his Movement for Democratic Change had proposed to Mugabe's ZANU-PF party that Tsvangirai take a powerful prime minister's role in any unity government. Tsvangirai said he would concede the presidency -- and the role of military commander in chief -- to Mugabe.

That would mean a major curbing of powers Mugabe has wielded for nearly three decades, since independence from Britain in 1980. But it also would leave Mugabe, accused of deploying soldiers and police against political dissidents, at least nominally in charge of the army. Under Tsvangirai's proposal, the president would only be able to exercise military power on the advice of the prime minister.

Zimbabwean military leaders have said they would refuse to recognize Tsvangirai's authority.

Tsvangirai came first in a field of four in the first round of presidential voting in March, but did not win by the margin necessary to avoid a runoff against second-place finisher Mugabe. Tsvangirai withdrew from the June 27 runoff because of attacks on his supporters blamed on Mugabe's party militants and security forces.

Mugabe held the runoff, and was declared the overwhelming winner, though the exercise was widely denounced.