Prime Minister Morgan Tsvangirai's party has called for an urgent summit of Southern African leaders to help enforce the agreement setting up Zimbabwe's unity government.
The summit should also "discuss the roadmap to an election and the guarantees to the legitimacy of this election," the Movement for Democratic Change (MDC) said in a resolution released after a meeting of its national council in Harare on Sunday.
The party's call reflects deep frustrations at what it sees as President Robert Mugabe's continued failure to implement the global political agreement (GPA) of September 2008.
The latest rise in tension within the government was generated by the decision of the Mugabe-appointed attorney-general, Johannes Tomana, to seek to overturn a court's acquittal of the MDC's nominee for deputy agriculture minister, Roy Bennett, on terrorism charges last week.
Tomana's chances of success are not rated highly by commentators, leading to suspicion that Mugabe's Zanu-PF party is simply seeking to delay indefinitely the swearing-in of Bennett.
Seventeen months after entering the unity government, the MDC said the "outstanding issues" which beset the unity government included Bennett's appointment, the disputed positions of Tomana and central banker Gideon Gono (both Mugabe loyalists), Mugabe's unilateral altering of ministerial mandates and the chairing of the Cabinet.
The MDC said the signatories to the GPA "must take measures to implement and execute" positions agreed upon by party leaders in April.
The party also attacked Zanu-PF's plans for the "indigenisation" of business enterprises, saying regulations aimed at forcing large companies to share assets with Zimbabweans were "elitist, selective and a mere vehicle for further enrichment of the rich few, self-aggrandizement, patronage, clientelism and further destruction of the economy."
It added: "The original indigenization and empowerment act should be repealed and be replaced by a new law that balances the overwhelming [imperative] of growing and investment in the economy against the fundamental obligation of broad-based empowerment."