The United Nations has warned supporters of Ivory Coast incumbent leader Laurent Gbagbo that an attack on the hotel headquarters of internationally recognised election winner Alassane Ouattara could restart civil war.
A pro-Gbagbo youth leader has said that Mr Ouattara and his supporters have until Saturday to "pack up their bags".
UN spokesman Martin Nesirky said Secretary-General Ban Ki-moon is "deeply alarmed" by these comments.
Mr Ban said an attack on the hotel could provoke widespread violence that could reignite civil war, and he called on those planning it to "refrain from such dangerous irresponsible action," Mr Nesirky said.
Under a peace deal after the 2002-03 civil war, the UN was tasked with certifying the results of the November 28 election. The UN declared Mr Ouattara the winner, echoing the country's own electoral commission chief.
But Gbagbo insists he won, pointing out that the Ivory Coast constitutional council declared him the winner. The council, which is led by a Gbagbo ally, did so after invalidating half a million ballots from Mr Ouattara strongholds in the north.
The United States and other world powers have insisted Gbagbo hand over power to Mr Ouattara. For many, the credibility of the international community is at stake if it is unable to ensure that Mr Ouattara takes power.
Chaos in Ivory Coast, once a West African economic powerhouse with skyscrapers dominating this seaside commercial centre, has already kept Gbagbo in power five years beyond his mandate.
The country's long-delayed presidential election was finally held in October. The vote was intended to help reunify the country .
Instead, the election has renewed divisions that threaten to plunge the country back into civil war. While Ivory Coast was officially reunited in a 2007 peace deal, Mr Ouattara still draws his support from the northern half of the country, where residents feel they are often treated as foreigners within their own country by southerners.