The United States has issued a new travel warning for the Central African Republic, where rebels have seized several towns over the past two weeks.

The warning from the State Department Monday urged Americans in the C.A.R. to review their personal security situation and consider taking advantage of commercial flights to safe locations.

The State Department also said that because of increased rebel activity, it has authorized the departure of non-emergency personnel from the capital, Bangui.

Monday, the C.A.R. government said it is ready for dialogue with the rebels provided that they withdraw from all the positions they have captured. The rebel alliance, known as Seleka, demanded a cease-fire.

Seleka has threatened to topple President Francois Bozize, whom it accuses of failing to fully implement a 2007 peace deal.

The rebel alliance has taken control of at least eight towns this month. On Sunday, it seized the central town of Bambari after a brief battle with government forces.

Seleka has continued to advance despite an offer by Chad to host peace talks and demands by the U.N. Security Council to cease hostilities and pull out of the captured cities.

Chad, a close ally of Mr. Bozize, has sent troops to the C.A.R. to support his government.