Harare - South Africa's president is starting talks with Zimbabwe's political leaders on his first trip as chief regional mediator.

President Jacob Zuma is on a crucial two-day visit to assess Zimbabwe's shaky coalition agreement a year after a power-sharing government was sworn in.

Zimbabwean President Robert Mugabe arrived Wednesday at a downtown hotel where Zuma is scheduled to meet later with Prime Minister Morgan Tsvangirai, Mugabe's longtime political rival.

Tsvangirai's party blames Mugabe for reneging on key provisions of the deal. Mugabe alleges Tsvangirai's party has failed to win concessions from its Western allies to remove targeted sanctions against Mugabe loyalists.