Zuma, who has become the most outspoken African leader on Zimbabwe, held talks in London with British Prime Minister Gordon Brown, one of Mugabe's harshest critics.

"We resolved on the crisis in Zimbabwe to redouble our efforts to secure early publication of election results," they said in a joint statement after their meeting.

"We call for an end to any violence and intimidation and stress the importance of respect for the sovereign people of Zimbabwe and the choice they have made at the ballot box."

No results have been announced from the March 29 presidential vote, while the outcome of a parliamentary poll is also in doubt because of partial recounts.

Movement for Democratic Change (MDC) leader Morgan Tsvangirai has said he won the presidential election outright and accused Mugabe of delaying results to rig victory.

Officials from the Zimbabwe Electoral Commission (ZEC) said Mugabe's ruling ZANU-PF and the MDC had each retained one constituency in the recount, the state-run Herald newspaper reported in its online version.

It quoted ZEC deputy chief elections officer Utoile Silaigwana as saying the recount would end by the weekend.

ZANU-PF lost 16 of those 23 constituencies in the original count, and needs to win nine more seats to overturn the MDC's parliament victory, the first in Mugabe's 28-year rule.

The government has clearly indicated it expects a presidential runoff -- necessary if neither candidate wins an absolute majority.

Zuma's backing for Brown's position over the Zimbabwe election could anger Mugabe, who accuses former colonial master Britain of plotting to oust him and sabotaging the economy with sanctions, which have failed to loosen his grip on power.

Britain called for an arms embargo on Zimbabwe while analysts dismissed as unlikely a proposal that Mugabe should lead a unity government until new polls.

The United States has led international calls for Africa to do more to end the Zimbabwe crisis. Washington's chief Africa diplomat, Assistant Secretary of State Jendayi Frazer, arrived in South Africa on a previously-arranged regional tour.

German Chancellor Angela Merkel added to growing pressure on Mugabe, who faces the toughest challenge to a rule that critics say has relied on tough security crackdowns and an elaborate patronage system.

"I think the situation for the people (in Zimbabwe) is unacceptable. We want a fair election result," she said at a news conference with Rwandan President Paul Kagame.

Zimbabweans just want relief from shortages of basic goods and the world's highest inflation rate of 165,000 percent.

Zuma and Brown promised that would come in the form of humanitarian aid and international efforts to secure Zimbabwe's economic recovery once the election process ends.

AFRICAN LEADERS

Zuma, who has distanced himself from the "quiet diplomacy" of South African President Thabo Mbeki over Zimbabwe, has called on African leaders to take action to unlock the stalemate.

Zimbabwe's neighbours, previously passive despite the collapse of the country's economy, took a harder line towards Mugabe this week, refusing to allow a Chinese ship to unload arms headed for the landlocked country.

Pro-government commentator Obediah Mukura Mazombwe add to uncertainty by suggesting Mugabe should lead a transitional government to end the deadlock while new polls were organised.

He said the solution should be mediated by Zimbabwe's neighbours. But analysts said Mugabe and his ZANU-PF party were pressing ahead with plans for a runoff vote against Tsvangirai.

Mazombwe holds no position in the ruling ZANU-PF party and his comments may not have official backing, analysts say.

In another opinion piece on Thursday, Herald political reporter Mabasa Sasa said a unity government was not feasible because ZANU-PF's radical nationalist policies were sharply different from the MDC's pro-Western stance.

Tsvangirai pressed ahead on a relentless regional drive seeking help from leaders to push aside Mugabe. On a visit to Mozambique on Wednesday, he rejected the idea of national unity government but said there were other options.

"The government of national unity does not arise because we won outright," he told a news conference.

The MDC, human rights groups and Western powers accuse ZANU-PF of launching a campaign of post-election violence. Tsvangirai says 10-15 MDC supporters have already been killed.