The two sides differ over cabinet positions
Talks between Zimbabwean President Robert Mugabe and the new Prime Minister Morgan Tsvangirai have failed to reach agreement on a unity cabinet.
The two signed a power-sharing deal nearly three weeks ago after disputed presidential elections in June.
It was agreed that Mr Mugabe - Zimbabwe's leader for three decades - would remain president while Mr Tsvangirai would become prime minister.
Both sides said they would meet early next week to resume negotiations.
A spokesman for Mr Tsvangirai's Movement for Democratic Change (MDC) said the discussions had been "frank and realistic" but that negotiations remained deadlocked.
Mr Mugabe's spokesman, George Charamba, said differences remained over who should hold the finance and home affairs portfolios.
'Threat to lives'
But the MDC said the disagreement was over the entire cabinet.
Zimbabwe's economy has spiralled into crisis in recent years. There are severe food shortages with the UN estimating that two million people are in need of food aid.
The inflation rate is the world's highest - last estimated at 11,200,000%.
The MDC spokesman, Nelson Chamisa, said the delay in forming a government was "a threat to people's lives".
"People are dying," he said. "The humanitarian response has to be activated and you need a functional government to do that."
Former South African President Thabo Mbeki has confirmed he will continue his efforts to mediate the deadlock in Zimbabwe.
Mr Mbeki brokered Zimbabwe's power-sharing deal before stepping down as president last week.