Zimbabwe's political leaders are said to be deadlocked over how to allocate Cabinet ministries as part of a power-sharing deal.
A spokesman, Nelson Chamisa, for the main opposition Movement for Democratic Change, MDC, says talks Thursday between President Robert Mugabe and MDC leaders ended without an agreement.
The spokesman says the matter has been referred to negotiators to resolve.
The power-sharing deal signed Monday calls for Mr. Mugabe's ZANU-PF party to receive 15 Cabinet positions in a national unity government. The MDC faction led by Morgan Tsvangirai would get 13 posts, while a smaller MDC faction would get the other three.
Opposition sources say ZANU-PF is demanding the most important ministries, such as finance and defense.
On Wednesday, Mr. Mugabe said the power-sharing deal was a "humiliation" for his party but insisted that ZANU-PF remains dominant.
State media Thursday quoted him as saying the ZANU-PF party remains "in the driving seat" as it enters the new government with the MDC.
The agreement calls for Mr. Mugabe to remain president and head of state, with Tsvangirai becoming prime minister. Arthur Mutambara, the head of the smaller MDC faction, would become deputy prime minister.
The agreement marks the first time Mr. Mugabe has agreed to give up some of his power during his 28-year rule.
Both he and Tsvangirai were under strong pressure to reach a deal so Zimbabwe can recover from its political and economic crises.
The country has been without an official government for months following disputed presidential elections. Tsvangirai won the most votes in the first round but pulled out of the run-off because of state-sponsored violence against his supporters.
Zimbabwe's economy meanwhile has continued to crumble, with inflation soaring to an estimated 11 million percent, and food shortages becoming more severe following a failed harvest.
Some information for this report was provided by AFP.