"It is time for Africa to step up," Rice told a news conference in Washington. "Where is the concern from the African Union and from Zimbabwe's neighbours about what is going on in Zimbabwe?"

African reaction has been subdued to events in Zimbabwe, where a 19-day delay in issuing results of a presidential poll has fuelled fears of violence, although regional leaders called last weekend for the outcome to be announced quickly.

The continent has largely taken its cue from President Thabo Mbeki, who has insisted on a softly softly diplomatic approach to President Robert Mugabe, despite the catastrophic collapse of Zimbabwe's economy.

Tsvangirai said on Thursday that Mbeki was no longer fit to mediate in the Zimbabwe crisis and he had asked for a completely new regional initiative by the Southern African Development Community (SADC).

"President Mbeki needs to be relieved from his duty," Tsvangirai told a news conference in Johannesburg, adding that Mugabe had "unleashed an orgy of violence against the people" after the election.

Mbeki led failed SADC mediation last year and has played down the gravity of the post-election deadlock.

Tsvangirai suggested that there may need to be a special United Nations tribunal to judge crimes committed in Zimbabwe.

"I think the current wave of violence against the people must stop and the only way to stop is that those who are committing those crimes must know that they must be answerable one day," he said.

POLICY SHIFT

The South African government made a major policy shift, calling for the results to be issued rapidly and saying it was concerned by the delay.

"The situation is dire," government spokesman Themba Maseko said on Thursday in Cape Town. "When elections are held and results are not released two weeks after, it is obviously of great concern."

Mbeki had previously said the electoral process must take its course and there was no crisis after the elections.

His stance was seen as backing Mugabe over the delay.

Although Mugabe's ZANU-PF party lost control of parliament for the first time in the vote, no results have been released from a presidential poll.

"The Zimbabweans need to be informed about those reasons for holding the results. But the most important thing is that the results need to be verified and released as soon as possible," Maseko said, briefing reporters on a Wednesday cabinet meeting.

The government of regional power South Africa had previously hesitated to join international expressions of concern about the delay in issuing the result of the vote, in which the opposition says Mugabe was defeated.

But ruling party leader Jacob Zuma, who toppled Mbeki from the head of the African National Congress last December, has made several statements calling for release of the results.

Maseko used similar language to Zuma in expressing concern about the results delay.

Mbeki is under criticism at home for his insistence on quiet diplomacy in dealing with the crisis in Zimbabwe, where the economy has collapsed, bringing hyper-inflation, shortages of food and fuel and 80 percent unemployment. Millions of people have fled to South Africa.

"South Africa, like the rest of the world, is concerned about the delay in the release of the results and the anxiety that this is generating," Maseko added.

The Zimbabwe Congress of Trade Unions (ZCTU) also expressed concern over the turmoil.

"The ZCTU is of the view that Thabo Mbeki is no longer a suitable person to mediate in the Zimbabwean crisis. We would prefer a situation where a retired African president takes up the role to persuade Mugabe to step down," it said.

The election outcome has now become embroiled in several legal cases that are further delaying a result. A court in Harare adjourned until Friday its hearing on an MDC challenge to a recount ordered in 23 parliamentary and presidential election constituencies.