The United Nations on Wednesday ordered more than 200 non-essential staff and families of other workers to leave Central African Republic because of a rebel offensive against the government.
Rebel coalition troops have stopped short of the capital, but UN spokesman Martin Nesirky said "their contradictory messages and their continued military offensive seem to indicate that they might be intent on taking Bangui."
"The temporary relocation is a precautionary measure to reduce our presence in the event the security situation further deteriorates in Bangui," he added.
The decision "will not detract from the ability of the United Nations to continue its support to the peace consolidation and development efforts in the Central African Republic," the UN spokesman said.
The United Nations has a major political mission in Central African Republic seeking to help the government overcome more than a decade of strife. More than 200 people are involved in the withdrawal order, a UN official said.
The Seleka coalition is made up of rebels who say President Francois Bozize has not honoured peace accords signed between 2007 and 2011 that offered financial support and other help for insurgents who laid down their arms.
On Wednesday, the rebels urged government troops to lay down their weapons.
The insurgents are about 300 kilometres (200 miles) from Bangui and have said they do not plan to take the capital, where Bozizi is being helped by Chadian forces.
Demonstrations against former colonial power France have added to tensions.
Nesirky said the head of the UN mission in the country, Margaret Vogt, "continues to engage the Government and the rebel leaders with a view to ensuring a ceasefire and initiating dialogue."
Meanwhile, statement said UN General Secretary Ban Ki-moon "strongly condemns the armed attacks on several towns" in the country by the Seleka coalition.
"These developments gravely undermine the peace agreements in place and the efforts of the international community to consolidate peace in the Central African Republic.
"The secretary general deeply regrets the loss of life and population displacement caused by the fighting."
Ban called on the rival sides to follow the decisions of the Central African summit on December 21, which he added could "provide a basis for a peaceful resolution of the dispute."
Ban reminded the Central African Republic's government "of its responsibility to ensure the safety and security of UN personnel and its premises."