Laurent Gbagbo, who is under growing pressure to step down as president of Ivory Coast after disputed elections last month, is demanding that United Nations peacekeeping troops leave the country immediately.
The UN mission, known has UNOCI, has not remained neutral in the election dispute, Gbagbo's spokesman said in a statement read on national television Saturday.
The United Nations and others in the international community say opposition leader Alassane Ouattara clearly won the Nov. 28 presidential runoff vote.
On Friday, UN Secretary General Ban Ki-moon called on Gbagbo to step down, European Union leaders threatened sanctions against the West African nation, and the United States announced it would impose "targeted sanctions" against Gbagbo, his family and associates, if the incumbent president did not leave office.
Gbagbo and Ouattara have set up rival governments and have the support of rival armed forces. Several hundred peacekeeping troops are on security duty for Ouattara, and the government has accused them of colluding with former rebels.
On Thursday in Abidjan, at least 20 people died during street clashes between supporters of Gbagbo and Ouattara.
On Saturday, masked men in military uniforms opened fire on the UN base after following guards back from a patrol, the UN mission said. No one at the base was harmed in the shooting.
The UN was invited by the government itself to supervise the vote and certify the outcome following a peace accord after Ivory Coast's 2002-03 civil war.