The UN's secretary-general has warned there is a "real risk" of a return to civil war in Ivory Coast after the disputed presidential election.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.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".'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).Laurent Gbagbo's offer of an international panel to solve the crisis came as a surprise at the end of a speech which he started by saying that he was the president of Ivory Coast. His speech has not changed and his mind is set. For him, the opposition has to be blamed for the violence and Alassane Ouattara simply does not want to respect the law. But Mr Gbagbo is someone who likes to surprise people. He made the offer of the election panel sound like a sign of goodwill, or even like a concession to "avoid another war".Many consider this latest offer as a chance for Mr Gbagbo to extend a five-year political stalemate during which the election was always postponed and he stayed in power. Forces loyal to Mr Gbagbo were obstructing Unoci operations, and had blockaded the 800 peacekeepers protecting Mr Ouattara, he warned."I am concerned that this disruption of life-support supplies for the mission and the Golf Hotel will put our peacekeepers in a critical situation in the coming days," he said."I therefore strongly appeal to member states who are in a position to do so to prepare to support the mission."Facing this direct and unacceptable challenge to the legitimacy of the United Nations, the world community cannot stand by," he added.The BBC's John James in Abidjan says roads leading to the lagoon-side hotel have been blocked and no supplies have been received for days.Mr Ban said that any attempt to "starve the United Nations mission into submission" would not be tolerated, and warned those who perpetrated such acts would be held accountable under international law. He also revealed Unoci had confirmed "mercenaries, including freelance former combatants from Liberia, have been recruited to target certain groups in the population", and that an arms embargo was being broken.