South African President Jacob Zuma travels to Zimbabwe on Thursday in a bid to ease tensions within the strained unity government, though analysts held out little hope for a breakthrough.

During his two-day visit, Zuma will meet with long-ruling President Robert Mugabe and his partner in government, Prime Minister Morgan Tsvangirai.

The political rivals formed a unity government in February but remain deadlocked noteably over the appointment of the Central Bank chief and the attorney general.

Tsvangirai's Movement for Democratic Change (MDC) also says the party's supporters are still harassed by police, despite guarantees of political freedoms in the unity accord.

"We hope that his visit will unlock and unblock the political logjam in our country," said MDC spokesman Nelson Chamisa.

Mugabe's party, however, blames western sanctions for undermining the government and sees the MDC concerns as a distraction, said Justice Minister Patrick Chinamasa.

"Our position is very clear. We hope our principal, President Robert Mugabe, tells President Zuma that the outstanding issues are that of sanctions and external interference," Chinamasa told AFP.

"The so-called outstanding issues, which are the issues of the (Central Bank) governor and the attorney general, are nowhere in the Global Political Agreement," said Chinamasa, who was Mugabe's lead negotiator in the unity talks.

"This is meant to distract attention from the inclusive government," Chinamasa added.

Ahead of his trip, the secretary general of Zuma's African National Congress (ANC) told reporters that the president plans to be vocal about Zimbabwe's problems, in contrast to the "quiet diplomacy" of his predecessor Thabo Mbeki.

"President Zuma will be more vocal in terms of what we see as deviant behaviour," Gwede Mantashe told reporters. "If there is deviant behaviour, we will be more vocal... but we will still engage."

While Mantashe avoided criticising Mugabe directly, he rattled off a list of problems that could be laid at the ageing leader's feet, including the harassment of MDC lawmakers and the violence in last year's presidential elections.

South Africa, Zimbabwe's biggest trading partner, is a key backer of the unity deal. Zuma's findings will likely inform discussions at the next summit of the Southern African Development Community (SADC) next month.

"President Zuma will be determined to use the visit to solve the outstanding issues" in the unity government, political analyst Okay Machisa said.

"He has a road map on the issues of Zimbabwe and he would want the local politicians to address the welfare of the people and not address their selfish needs."

Tsvangirai met Zuma in Johannesburg three weeks ago to brief him on the troubles within the unity government.

On Mugabe's side, the 85-year-old leader faces pressure within his own ZANU-PF to avoid any further compromises that would further erode the party's power.

The party's politburo earlier this month publicly called on Mugabe "to resist any pressures intended to prejudice the party."

The feuding has hindered Zimbabwe's drive to win 8.3 billion US dollars in aid to revive the civil service and jump start the shattered economy.

To date the inclusive government has raised just over two billion dollars, mostly coming from continental organisations and China.

One South African government official, in Harare ahead of the trip, insisted Zuma was coming to seek compromise.

"There are issues which have to be addressed, but as South Africa we believe that every problem presents a new opportunity," the official told AFP.

"Zimbabwe is far much better today than what it was last year, so we believe a compromise will eventually be found."