An envoy from Alassane Ouattara, regarded internationally as the winner of the disputed presidential election in Ivory Coast, is reported to have had his credentials accepted at the United Nations.
The UN has repeatedly asked Laurent Gbagbo to step down, but Mr Gbagbo, who controls the country's army, refuses to quit.
Guillaume Soro, the prime minister in Mr Ouattara's provisional government, says the only solution now is for an international force to intervene.
However, Mr Gbagbo is demanding that UN peacekeepers leave.
The World Bank has cut off funding to Ivory Coast, amid growing fears the chaos there could spiral into a full-blown civil war.
Mr Gbagbo has blockaded Mr Ouattara, the winner of the November election, in a hotel where security is being provided by UN peacekeepers.
The governments of France and Germany have warned their remaining nationals to leave the country.