MDC secretary general accuses President Mugabe of imprisoning Mr Tsvangirai
Zimbabwe's main opposition party has shunned regional talks on the country's crisis after its leader, Morgan Tsvangirai, was denied a passport.
He was instead issued an emergency travel document to go to Swaziland but his officials called this an "insult".
Zimbabwe's information minister called the boycott a "gimmick".
The summit was called after four days of talks failed to lead to an agreement on how the opposition MDC and Zanu-PF should allocate cabinet jobs.
Mr Tsvangirai and President Robert Mugabe agreed to share power last month, after a long stand-off over disputed elections earlier this year.
But Mr Tsvangirai's Movement for Democratic Change (MDC) has accused Mr Mugabe of trying to grab power by allocating all the key ministerial positions to his Zanu-PF party.
Swaziland's King Mswati III has sent a private jet to pick up Mr Tsvangirai in Harare but it remains unclear whether he will take up the offer.
MDC Secretary General Tendai Biti said the difficulties Mr Tsvangirai has had getting travel documents made it clear that Mr Mugabe was not ready to share power, the Associated Press news agency reports.
"The issue of a passport is a mere symptom," he said.
"The real problem [is] there is no readiness on the part of Zanu-PF to engage in a cooperative government with Morgan Tsvangirai and the MDC."
Mr Biti said the MDC would not send anyone else to Swaziland and called for a full summit of all 12 members of the regional body, the Southern African Development Community (SADC).
'Trust'
King Mswati is a member of the SADC security panel, along with the leaders of Angola and Mozambique.
Robert Mugabe said his allies should hold the key posts in the cabinet
Mr Mugabe is there, along with the leader of a smaller MDC faction.
Mr Tsvangirai has not had a normal passport for several months.
He was reportedly given an emergency document only valid for a single trip to Swaziland. However the only way of getting from Zimbabwe to Swaziland is via South Africa.
But Zimbabwean Information Minister Sikhanyiso Ndlovu dismissed the MDC claim as "a gimmick", reports the Reuters news agency.
"He has been given a travel document. South Africa is mediating, how can they deny him passage?"
Mr Mugabe's spokesman George Charamba said Mr Tsvangirai had not been given a passport because "Zimbabwe is running out of paper... because of sanctions", reports the AFP news agency.
On Sunday, Mr Tsvangirai said the deal was sound but there was "a problem of trust" between himself and Mr Mugabe.
Difficult negotiations
Mr Tsvangirai described last week's talks in Harare as "a one-man monologue" by Mr Mugabe.
The efforts to reach a deal were mediated by former South African President Thabo Mbeki.
Mr Mbeki oversaw the signing of the power-sharing framework deal a month ago, but has since stepped down from office in South Africa and is now attempting to construct Zimbabwe's new government as a private citizen.
MINISTRY DIVISION
Zanu-PF: 15 ministries including:
Defence
Foreign affairs
Justice
Local government
Media
Main MDC: 13 ministries including:
Constitutional and parliamentary affairs
Economic planning and investment promotion
Labour
Sport
Arts and culture
Science and technology development
MDC (Mutambara): Three including:
Education
Industry and commerce
Source: Government gazette
The BBC's Jonah Fisher, following events from South Africa, says the power-sharing deal now teeters on the brink of collapse.
President Mugabe has allocated the main ministries, including defence, home, foreign affairs, and justice, to Zanu-PF.
As well as finance, the MDC also insisted it should have home affairs - and control of the police - if Zanu-PF had defence.
They say they need home affairs to give them a stake in the country's security forces, our correspondent says.
The MDC accused the security services of taking part in violent attacks on its supporters before June's presidential run-off election.
Reports on Friday suggested that Mr Mugabe might have agreed to let the MDC take the key post of finance minister, but that he would not give it home affairs.
Finance is one of the most crucial posts, as Zimbabweans hope the power-sharing deal will lead to action to tackle the economic crisis.
Donors have promised to help finance a recovery plan but they are unlikely to release funds if a Zanu-PF minister is in charge.
At 231,000,000%, Zimbabwe has the world's highest rate of annual inflation, while some two million people need food aid. Aid agencies warn that figure could double within the next few months.
According to the original power-sharing deal agreed last month, 15 ministries are to be allocated to Zanu-PF, 13 to the MDC, and three to a smaller MDC faction led by Arthur Mutambara.
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