The government of disputed President Laurent Gbagbo has banned UN and French peacekeeping aircraft from flying over, or landing in Ivory Coast.
The announcement came as Alassane Ouattara, recognised by the UN as the winner of November's poll, went to Ethiopia for a meeting on the crisis.
The African Union is set to call for Mr Ouattara to lead a unity government, the BBC understands.
Mr Gbagbo has refused to attend the African Union gathering.
The BBC's Uduak Amimo at the AU summit in the Ethiopian capital, Addis Ababa, says it is not clear if the proposed plan for a government of national unity would retain a role for Mr Gbagbo but it would certainly include some of his loyalists.
A team of five African heads of state has been considering how to resolve the political impasse amid warnings the country is sliding back into civil war.
Last year's long-delayed elections had been supposed to reunify the country - once the richest in West Africa - which has been divided since a 2002 civil war.
The UN-backed electoral commission says Mr Ouattara won presidential elections in November, but the Constitutional Council overruled it, citing rigging in the north. BBC News
