Officials briefly confiscated the passports of Zimbabwe's top opposition leader and two aides as they tried to fly to South Africa Thursday to attend a regional summit.

The seizure kept the three from flying Thursday, but opposition leader Morgan Tsvangirai, his secretary general Tendai Biti and a third Movement for Democratic Change official still have time to get to the weekend summit of the Southern African Development Community.

"They have confiscated my passport," Tsvangirai told The Associated Press as he left the airport. Shortly afterward, party official Nqobizitha Mlilo said the passports had been returned.

Attempts to reach Zimbabwean government officials for comment were not immediately successful.

In South Africa, presidential spokesman Mukoni Ratshitanga said South African officials appealed to Zimbabwean officials to allow the opposition team attend the summit.

In Washington, U.S. State Department spokesman Robert Wood expressed concern about the brief confiscation of the passports, but said U.S. officials expected Tsvangirai to travel to South Africa on Saturday, the day the summit begins.

South African President Thabo Mbeki has been mediating power-sharing talks between Zimbabwean President Robert Mugabe and the opposition, and their standoff is expected to be a main topic at the SADC summit.

In a statement Thursday, Tsvangirai's party called on the SADC, the African Union and the broader international community "to take a strong position against Mugabe."

Biti has been Tsvangirai's top negotiator in the deadlocked power-sharing talks, with Tsvangirai and Mugabe each claiming he should lead any coalition.

Tsvangirai left the talks late Tuesday, prompting speculation that he had walked out. But he said in a statement Wednesday that said negotiations would continue.

On Thursday, Tsvangirai's party said the "latest antics" over the passports call Mugabe's commitment to a negotiated settlement into question.

"Mugabe continues to preach dialogue and to act war," it said in a statement.

The Herald, a newspaper considered a Mugabe mouthpiece, derided Tsvangirai's claim to leadership Thursday, accusing him of "parroting" Western arguments and accusing him of blocking a power-sharing deal.

Tsvangirai beat Mugabe and two other candidates in the March 29 presidential elections, and since has insisted that any power-sharing agreement recognize that result.

However, the official tally did not give Tsvangirai the 50 percent plus one vote needed to avoid a runoff. He withdrew from the June runoff, citing state-sponsored violence against his supporters.

Mugabe held the widely denounced runoff anyway and claimed an overwhelming victory on which he now bases his claim to leadership.

Mugabe reportedly wants to keep his authority as president, while Tsvangirai reportedly wants executive powers as prime minister, including the right to chair Cabinet meetings.

The coalition would likely govern for a period short of Zimbabwe's five-year presidential term, and one of its task would be new presidential elections.

The Herald said the March elections were "inconclusive" and overturned in June.

"Insiders said Tsvangirai was parroting the same sentiments expressed by the United States, the European Union and Britain," the country's former colonial power, The Herald said.

Western nations have been among Mugabe's sharpest critics, saying he is a dictator who has ruined a once promising economy. Wood said Thursday that any agreement reached in the negotiations should reflect "the will of the Zimbabwean people as reflected in the March 29 election."

The Herald also outlined 13 measures it said Tsvangirai's team agreed upon during the negotiations, including a denunciation of Western sanctions against Mugabe's government and a call on Britain to help fund land reform.

But the paper said Tsvangirai on Tuesday presented "a fresh position paper titled `Notes on the Dialogue to Date,' which appeared to repudiate all the agreements already signed and would have set back the status of the negotiations by weeks."

Opposition officials have refused to discuss specifics, citing a news blackout on the negotiations ordered by Mbeki. The Herald article appeared to be an attempt to pressure Tsvangirai by portraying him as an obstacle to resolution.

Zimbabwe's crisis has undermined regional stability and split Zimbabwe's neighbors. Botswana has threatened to boycott the weekend summit if Mugabe attends as president, and on Thursday sent only lower-ranking officials to a ministerial preparation meeting.

As she opened Thursday's meeting, South African Foreign Minister Nkosazana Dlamini Zuma acknowledged Zimbabwe's crisis presented a challenge, but called on SADC not to be divided.

"We will be very much weaker if we lose ... unity and cohesion," she said.