Power-sharing talks have ended in Zimbabwe without agreement between the opposition and President Robert Mugabe.

All sides had called Monday's talks in Harare the last chance to end a standoff over key Cabinet posts that is keeping a unity government from taking office.

Opposition leader Morgan Tsvangirai said after the talks ended late Monday that this was the darkest day of his life. He said the opposition is committed to a power-sharing government, but Mr. Mugabe's party must show it is also sincere by making concessions.

President Mugabe said the talks will go on but did not say when they will resume.

Tsvangirai, Mr. Mugabe, and the head of a smaller opposition faction, Arthur Mutambara, were trying to reach agreement on several issues, including which party controls what Cabinet jobs.

Southern African leaders, of the South African Development Community, say they will hold a summit next week in Botswana to talk about the impasse.

The political standoff is doing nothing to help Zimbabwe's economic and humanitarian crises, which includes a food shortage, sky-high inflation, and a cholera epidemic that has so far killed more than 2,200 people.

Zimbabwe's state-run "Sunday Mail" newspaper quoted Mr. Mugabe Sunday as threatening to break off talks unless the opposition agreed to the ruling party's terms for a final deal.

Tsvangirai's party says it will not be "bulldozed" into giving up on its demands, which include the release of some 30 activists who have been detained on what the opposition considers trumped-up charges.

The activists have told courts that they have been tortured in police custody.  

Mr. Mugabe finished second to Tsvangirai in the presidential election last March, but neither candidate took enough votes to avoid a second-round run-off. Tsvangirai pulled out of the run-off, citing killings and beatings of his supporters.

Some information for this report was provided by AFP and Reuters.