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

Mugabe had until now shown little interest in talks and his government had scoffed at Movement for Democratic Change leader Morgan Tsvangirai's call Wednesday to work together to form a transitional authority.

"We remain open to discussion with the MDC," Mugabe said while speaking at a campaign rally in Chitungwiza, about 15 miles south of the capital.

But Zimbabwean Deputy Information Minister Bright Matonga said Mugabe's words did not indicate that the leader was softening toward the opposition. He said Mugabe had always insisted that the runoff must take place in accordance with the country's constitution.

Matonga would not say how soon after the election the two parties would meet, saying that if Mugabe won the election he would address the nation soon afterward.

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

World leaders have dismissed the 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.

Tsvangirai won the first round of the presidential election on March 29, but did not gain an outright majority against 84-year-old Mugabe. That campaign was generally peaceful, but the runoff has been overshadowed by violence and intimidation, especially in rural areas. Independent human rights groups say 85 people have died and tens of thousands have been displaced from their homes, most of them opposition supporters.

Zimbabwe opposition party's No. 2 official, who has been charged with treason, was granted bail and released from jail Thursday.

Tendai Biti was required to surrender his passport and the title to his home and report to police twice a week in addition to bail set at 1 trillion Zimbabwean dollars, or about $100, lawyer Lewis Uriri said.

Biti returned to his home in the capital late afternoon, two weeks after he was jailed looking tired and frail but still sounding defiant.

"Some people stay 27 years in prison so two weeks is nothing," he said in an interview with Associated Press Television News. "It wasn't easy though but we have to continue fighting."

Anti-apartheid icon Nelson Mandela, who criticized Zimbabwe's leadership Wednesday, spent 27 years in a jail before becoming South Africa's first democratically elected president.

On Thursday, both the government and the opposition reacted strongly to Mandela's criticism, 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, 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.

Mugabe was lauded early in his rule for campaigning for racial reconciliation. But in recent years, he has been accused of ruining the economy and holding onto power through fraud and intimidation.

The official inflation rate was put at 165,000 percent by the government in February, but independent estimates put the real figure closer to 4 million percent.

Since the first round of national elections on March 29, shortages of basic goods have worsened, public services have come to virtual standstill, power and water outages have continued daily, and streets and highways have crumbled.

The economic slide of what was once the region's breadbasket has been blamed on the collapse of the key agriculture sector after often-violent seizures of farmland from whites. Mugabe claimed he ordered the seizures, begun in 2002, to benefit poor blacks. But many of the farms instead went to his loyalists.