In a speech to the UN General Assembly on Tuesday, Mr Ban said he was worried about the 10,000-strong mission in Ivory Coast (Unoci).

Ban Ki-moon said the incumbent, Laurent Gbagbo, was illegally trying to expel the UN's peacekeeping force after it recognised Alassane Ouattara as victor.

Forces loyal to Mr Gbagbo were obstructing Unoci operations, and had blockaded the 800 peacekeepers protecting Mr Ouattara, he warned.

Earlier, an ally of Mr Gbagbo warned the peacekeepers that they could be treated as rebels if they did not go. And in his first TV address since the poll Mr Gbagbo stressed his legitimacy.

He also offered to let a panel representing international powers examine the results of the election.

Mr Gbagbo said Mr Ouattara could leave the Golf Hotel in Abidjan, where he has set up his headquarters, protected by the UN.

The army meanwhile announced the lifting of a nightly curfew, so families could "enjoy the end of year holidays and the New Year".