But the leaders said they believe there is a basis for a power-sharing deal, and called on both sides to sign it.

South African President Thabo Mbeki, the lead Zimbabwe negotiator for the 14-member Southern African Development Community (SADC), said the group wants Zimbabwe's government leaders and opposition to "conclude the negotiations ... as a matter of urgency."

"It's clearly not possible to say when negotiations will be concluded," he told reporters after the summit. "It's a matter of negotiating parties reconvening."

As the meeting began on August 16, hundreds protested outside, angry at the inclusion of Zimbabwe's President Robert Mugabe. They called on SADC not to recognize Mugabe as a head of state after June's widely discredited presidential runoff that returned the longtime president to power.