"It should take place in the next couple of weeks to resolve outstanding issues by the end of the year."
Enlarging the existing AU peacekeeping force in Darfur will take place in three phases over an unspecified period of time, Annan told journalists.
Sudan has not given its unreserved approval to the plan because officials at Thursday's meeting needed to consult with their superiors in the Sudanese capital, said Abdul Mahmoud Abdelhaleem, Sudan's ambassador to the UN.
Some of the issues the officials could not decide on immediately included who Sudan would accept to be in command of such an expanded peacekeeping force.
An African Union Peace and Security Council meeting will be held in the Republic of Congo on November 24 during which Sudan is expected to present its final views on what was agreed on in Ethiopia on Thursday, Annan said.
Annan had wanted UN peacekeepers to replace a beleaguered AU force in Darfur. Sudan has so far blocked a UN contingent.
Annan wants to try to stop the bloodshed in Darfur before he leaves office on January 1.
The meeting brought together senior officials from the AU, the Arab League, the European Union, Sudan, the United States, China, Russia, Egypt, France and half-a-dozen African countries.