Zimbabwe's President Robert Mugabe and Prime Minister Morgan Tsvangirai failed to resolve their differences during their first meeting since Mr. Tsvangirai's party boycotted the unity government 10 days ago.
A spokesman for the prime minister's MDC party said Monday the two leaders are "worlds apart" on key issues affecting the unity government.
Spokesman Nelson Chamisa said the MDC will await the outcome of mediation efforts by the Southern African Development Community. But if the regional bloc's mediation fails, he added, the MDC will start preparing for new elections.
There was no immediate comment on the talks either by Mr. Mugabe or his ZANU-PF party.
Mr. Tsvangirai said on October 16 that the MDC would no longer work with ZANU-PF, which he says has been a dishonest and unreliable partner.
This followed the re-detention of one of Mr. Tsvangirai's aides - white farmer Roy Bennett - on terrorism charges. And last week on Friday, police raided a home belonging to Mr. Tsvangirai's party, raising tensions further.
The MDC charges that Mr. Mugabe is acting unilaterally, and that ZANU-PF is harassing key MDC officials - actions that are placing great strains on the unity government, which has seen nearly constant disagreements between the two political blocs since it was formed in February.
The unity government has made progress toward reviving Zimbabwe's collapsed economy, but Western governments are refusing to give significant aid until sweeping political and economic reforms are put into place.
Critics accuse Mr. Mugabe of driving the economy into ruin with his policies, especially the seizure of white-owned farms for redistribution to blacks.
Some information for this report was provided by AFP and Reuters.