"All the negotiating teams are back. Nothing was achieved in the latest round of engagement in South Africa to break the deadlock. We remain where we were," the Movement for Democratic Change (MDC) spokesman Nelson Chamisa told Reuters.
Mbeki’s spokesperson Mukoni Ratshitanga told Reuters on Sunday that the dialogue would continue, but declined to give details.
"It is a continuous process, not a single event," Ratshitanga said.
The power-sharing talks have stalled over how executive power should be shared by President Robert Mugabe and MDC leader Morgan Tsvangirai, who refused to sign an agreement that would have made him prime minister two weeks ago.
Tsvangirai has protested against the proposed deal, saying it did not give him enough executive powers in government.
The opposition leader beat Mugabe in a March 29 election but fell short of enough votes to avoid a run-off vote, which was controversially won by Mugabe after Tsvangirai pulled out citing violence and intimidation against his supporters.
ZANU-PF officials were not immediately available to comment on the matter, but state media reported on Sunday that Mbeki would soon "chart a way forward" in the talks.
"I can confirm that we went to South Africa for separate bilateral discussions with the facilitator," state media quoted Justice Minister Patrick Chinamasa, ZANU-PF’s chief negotiator, as saying.
"The meeting was convened because the facilitator wanted to search for a way forward," Chinamasa added.
The MDC has accused Mugabe of flouting a framework agreed by the negotiating parties not to convene parliament or appoint a cabinet.
The veteran ruler, who was last week jeered and heckled by opposition lawmakers as he officially opened parliament, has said he would soon appoint a new government.
"Mugabe is showing no respect for Southern African Development Community (SADC), no respect for the dialogue," said Chamisa, adding that the MDC would lobby the African Union (AU) and the United Nations not to recognise Mugabe as Zimbabwe’s president.
"As far as we are concerned, to the extent that the dialogue has not been concluded, there is no legitimate government in Zimbabwe so he should not go to the UN and AU posing as the President of Zimbabwe. We will be taking up this matter with these organisations (UN and AU)," Chamisa added. Reuters