In a surprising shift before an internationally condemned presidential runoff, President Robert Mugabe said Thursday he was "open to discussion" with Zimbabwe's opposition.

Mugabe, who spoke at a campaign rally Thursday, had until now shown little interest in talks and his government had scoffed at opposition leader Morgan Tsvangirai's call Wednesday to work together to form a transitional authority.

Tsvangirai, the only candidate facing Mugabe in the runoff, announced Sunday he was withdrawing from Friday's vote because state-sponsored violence against his Movement for Democratic Change had made it impossible to run. He then fled to the Dutch embassy for safety.

World leaders have dismissed Friday's runoff as a sham, but electoral officials say the election will go ahead with Tsvangirai's name on the ballot.

Prior to Mugabe's comments, Tsvangirai was quoted Thursday as saying negotiations won't be possible if Mugabe goes ahead with runoff.

"Negotiations will be over if Mr. Mugabe declares himself the winner and considers himself the president. How can we negotiate?" Tsvangirai said in an interview with the British newspaper The Times.

In the capital, Harare, opposition members fled to the South African embassy, fearing for their lives. Authorities blocked the road to the embassy's main entrance and stationed riot police on a nearby highway to keep more opposition members from seeking refuge.

Ronnie Mamoepa, a spokesman for South Africa's Foreign Ministry, said the embassy held about 180 people, including women and children, by Thursday morning. The ambassador was working with aid groups and Zimbabwean officials to find sanctuary for them, as well as food, blankets, and other supplies.

Some of the refugees could be seen sitting in the sun or sleeping in the embassy's parking lot.

Both the government and the opposition reacted strongly Thursday to Nelson Mandela's criticism of Zimbabwe's government, with Mugabe's spokesman dismissing the comments and Tsvangirai reverently welcoming them.

Information Minister Sikhanyiso Ndlovu said Mandela was only bowing to Western pressure when he spoke of Zimbabwe's "tragic failure of leadership" at a London fundraiser. Keenly aware of Mandela's status as anti-apartheid icon, Ndlovu condemned the West for pressuring African leaders, not Mandela.

Mandela rarely differs publicly with South African President Thabo Mbeki, but many Africans have questioned Mbeki's unwillingness to criticize Mugabe, his neighbor.

"We appreciate the solidarity from Nelson Mandela," Tsvangirai said. "It is something we cherish."

Tsvangirai spoke to Britain's Sky News from the Dutch Embassy in Harare, where he sought shelter last weekend amid mounting political violence blamed primarily on Mugabe's government.

Meanwhile, a huge flap arose over whether or not Tsvangirai called for U.N. peacekeepers to come to Zimbabwe. The Herald, a Zimbabwean government mouthpiece, on Thursday accused Tsvangirai of calling "for military intervention in Zimbabwe disguised as peacekeepers."

Tsvangirai issued a statement late Wednesday saying he did not write a commentary that appeared in the British newspaper The Guardian under his name calling for United Nations peacekeepers to come. He said The Guardian was assured by "credible sources" that he had approved the article, but he had not.

A Tsvangirai aide, George Sibotshiwe, said Thursday his party was trying to determine how the commentary was given to The Guardian under Tsvangirai's name.

Tsvangirai had been asked about the essay earlier Wednesday and did not disavow it then, though he did stress that a call for peacekeepers was not a call for military intervention.

Sibotshiwe, the spokesman, said Tsvangirai did not equate peacekeepers with military intervention.

"We still need peacekeepers," Sibotshiwe said.

Mugabe continued to campaign like an actual presidential race was taking place. The Herald reported Thursday he had urged crowds north of Harare to "vote for the ruling party to show the world their resolve to defend the country's sovereignty and independence."

Mugabe has become increasing defiant in the face of international condemnation over his mismanagement of the southern African nation's economy.

"Robert Mugabe has stopped listening to the whole world," opposition spokesman Sibotshiwe said. "Robert Mugabe does not care about African solidarity. He only cares about African solidarity when it is convenient."

The leaders of Swaziland and Tanzania on Wednesday urged Zimbabwe to postpone the runoff, saying violence and restrictions on the opposition had not created the conditions for a free and fair vote. But The Herald quoted officials here Thursday as rejecting that call.

Meanwhile, Zimbabwe's No. 2 opposition leader was granted bail at a hearing Thursday.

Tendai Biti, secretary general of the Movement for Democratic Change, had been jailed since flying back to Zimbabwe from South Africa on June 12. He was charged with treason, which carries the death penalty, as well as with publishing false statements, insulting the president, among other things.

Lawyer Lewis Uriri said Biti paid bail of $100 and had to surrender his passport, the title to his home and report to police twice a week. He said Biti was waiting for the paperwork to complete his release.