"There is progress on the dialogue that has been made between the parties," Lindiwe Zulu, spokesperson for the mediators, said.
"While we are anxious that all issues are resolved, the good thing is that they are talking," she addded.
"As far as we are concerned and as far as President (Jacob) Zuma is concerned, the earlier the issues are resolved, the better for the welfare and social status for the people of Zimbabwe."
The mediators including Zulu, who is the South African president’s international adviser, returned from Zimbabwe on Wednesday, after holding a series of meetings with the negotiators from Mugabe’s Zanu-PF and the two factions of the opposition MDC.
The delegation, which also includes former cabinet ministers Charles Nqakula and Mac Maharaj, met last week with Mugabe at his State House offices.
A report will be presented to Zuma to brief him about the visit, Zulu said.
Raft of disputes
The unity government created in February has been plagued by a raft of disputes that led Tsvangirai to boycott cabinet meetings for three weeks in October.
Last month, regional leaders of the Southern African Development Community (SADC) ended the standoff at a special summit in Mozambique, tasking Zuma with helping the parties resolve their differences.
SADC gave the parties a 30-day deadline to resolve the issues, but this has been missed. Negotiations will however continue, said Zulu.
Among the issues contested by the rival parties are the appointment of the central bank governor and the attorney general, as well as the naming of provincial governors and the removal of a Western travel ban and asset freeze on Mugabe and his inner circle.
Zuma earlier this month named a new team to take over the regional mediation role previously held by former South African president Thabo Mbeki, who brokered the power-sharing deal signed last year that created the unity government.