Tsvangirai announced on Friday that his Movement for Democratic Change (MDC) party would disengage from Mugabe’s "dishonest and unreliable" ZANU-PF party in the country’s unity cabinet set up in February.
Analysts say the MDC’s decision may not mean the end of the power-sharing government but it will put pressure on the Southern African Development Community (SADC), the regional body under whose auspices former South African President Thabo Mbeki brokered a settlement in Zimbabwe last year.
The MDC boycott has sparked the country’s biggest political crisis since the formation of the new administration in February this year, but Mugabe’s spokesman George Charamba said on Sunday Mugabe would chair a cabinet meeting on Tuesday without the MDC.
An aide told Reuters that Tsvangirai would on Tuesday meet Mozambican President Armando Guebuza, who chairs the SADC’s political panel on defence and security, in Maputo.
Tsvangirai would also this week travel to the Democratic Republic of Congo for a meeting with President Joseph Kabila, current SADC chairman, to urge the body to force Mugabe to honour the power-sharing agreement signed last year.
"He (Tsvangirai) will be meeting SADC leaders, including Jacob Zuma (South Africa) and Jose Eduardo dos Santos (Angola)," the aide said, refusing to be named.
"We are doing all this to explain to the region the problems affecting the unity government. They (SADC) are the guarantors of this agreement."
Tsvangirai may travel to South Africa later on Monday, although spokesman James Maridadi was not immediately available for comment.
The aide said there were no immediate plans for a meeting of the SADC troika on defence and security involving Mugabe and Tsvangirai to resolve the political dispute.
The MDC accuses Mugabe of failing to implement the terms of last year’s political agreement, such as the appointment of senior government officials, including a new central bank governor and the attorney general, and the swearing-in of Tsvangirai’s nominee for the post of deputy agriculture minister, Roy Bennett.
Bennett is facing charges of illegal possession of arms for purposes of committing terrorism and banditry and was last week detained in prison after he was indicted to face trial. He was later released on bail.
Mugabe has refused to swear him in until he is acquitted but Bennett, who denies the charges that carry a maximum death sentence upon conviction, says he has been targeted as part of a wider political campaign against the MDC.
The formation of the fragile unity government had raised hopes among Zimbabweans of an end to a devastating economic crisis and political tensions that fanned electoral violence.
Western donors have been sceptical about Mugabe’s commitment to genuinely share power with Tsvangirai and continue to hold on to badly needed aid to rebuild collapsed schools, hospitals and public infrastructure.