Jendayi Frazer speaks to the BBC about Zimbabwe's crisis
The US will not recognise the outcome of Friday's presidential election run-off in Zimbabwe, a senior state department official has said.
Jendayi Frazer said Robert Mugabe could not claim a credible victory while opposition members were being killed.
Opposition leader Morgan Tsvangirai has pulled out due to the violence but Mr Mugabe says it will go ahead.
A group of southern African leaders are holding an emergency meeting in Swaziland to discuss the crisis.
Presidents and senior officials from Swaziland, Angola and Tanzania - members of the Southern Africa Development Community (Sadc) peace and security committee - are expected to discuss the possibility of a transitional government for Zimbabwe.
The BBC's Mike Wooldridge says there had been speculation South African President Thabo Mbeki might attend, as he is Sadc's chief mediator.
But he has already spoken to some of those attending the meeting and that input will be added to discussions, our correspondent adds.
We cannot, under these conditions, recognise the outcome if, in fact, this run-off goes forward
Meanwhile, UK-based mining giant Anglo American is reported to be investing $400m (£200m) in a Zimbabwe platinum mine, a UK newspaper says.
The project, in the central district of Unki, would be the largest foreign investment in the country, the London Times said.
News of the investment comes amid mounting calls for increased sanctions on Zimbabwe's regime.
Mr Tsvangirai, who has been taking refuge in the Dutch embassy in Harare since late Sunday, has called for UN peacekeepers to enter Zimbabwe and protect MDC supporters until a new election can be held.
Writing in Britain's Guardian newspaper, Mr Tsvangirai says the standard diplomatic approach has failed to resolve Zimbabwe's crisis and calls for a more "activist strategy".
The opposition Movement for Democratic Change (MDC) says some 86 of its supporters have been killed and 200,000 forced from their homes by militias loyal to the ruling Zanu-PF party. The government blames the MDC for the violence.
Ms Frazer, Assistant US Secretary of State for African Affairs, said Washington would not recognise the result of any vote held on Friday.
"People were being beaten and losing their lives just to exercise their right to vote for their leadership so we cannot, under these conditions, recognise the outcome if, in fact, this run-off goes forward," she said.
Her comments came amid growing international condemnation of the political crisis in Zimbabwe.
'Open to talks'
The Southern African Catholic Bishops' Conference issued a statement saying "the politically-motivated violence, intimidation and torture have made a just and fair run-off presidential election virtually impossible".
"We are deeply concerned at this situation and warn that unless there is a unified effort from the International Community with the leadership of Southern African Countries, the hopeless situation of violence, famine and uncertainty will result in a vast humanitarian crisis that will engulf the whole Southern African region."
ZIMBABWE AND ITS NEIGHBOURS
Zimbabwe's opposition wants neighbouring countries to persuade
Robert Mugabe to step down. So how are relations changing?
South Africa's leader Thabo Mbeki remains the key mediator. He has not
criticised Mr Mugabe, despite pressure from the ruling ANC.
Zambian President Levy Mwanawasa called Zimbabwe a "regional
embarrassment", before suffering a stroke on 29 June.
Angola's President Jose Eduardo dos Santos is one of Robert Mugabe's closest allies. He has urged Mr Mugabe to end the violence.
Botswana said Zimbabwe's 27 June run-off vote was so flawed by violence
that it could not be considered legitimate.
Namibia is an ally of Robert Mugabe. It wants to re-distribute white-owned farms to black villagers. It has not criticised the violence.
Mozambique has hosted some white farmers forced out of Zimbabwe when their land was seized. It is seen as sympathetic to the opposition.
Tanzania's ruling party has a history of backing Robert Mugabe's
Zanu-PF party. Its foreign minister has condemned the violence.
DR Congo's President Joseph Kabila is an ally of Robert Mugabe who
sent troops to help his father, Laurent Kabila, fight rebels.
Malawi is seen as neutral. But 3m people from Malawi are in Zimbabwe
and many were badly hit by the farm invasions.
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