The opposition Movement for Democratic Change in Zimbabwe says talks with the government of President Robert Mugabe aimed at reaching a power-sharing deal have stalled.
The Movement for Democratic Change says the talks deadlocked over what position opposition leader Morgan Tsvangirai should hold.
They also disagree over how long a national unity government should remain in power.
The talks began last Thursday after Mr Mugabe and Mr Tsvangirai signed a framework for discussions to end a deadlock over Mr Mugabe's re-election on 27 June in a one-man election.
Mr Tsvangirai won the first round election on 29 March.
The Southern Africa Development Community and the African Union want a power-sharing deal.
Mr Mugabe has ruled Zimbabwe since 1980.