WASHINGTON - President Obama said Saturday that 50 U.S. troops have deployed to the African country of Chad to help evacuate U.S. citizens and embassy personnel from the neighboring Central African Republic's capital of Bangui in the face of rebel advances toward the city.

Obama informed congressional leaders of Thursday's deployment in a letter Saturday citing a "deteriorating security situation" in the Central African Republic.

The evacuation of the U.S. diplomats comes after criticism of the Obama administration's handling of diplomatic security at its consulate in Benghazi, Libya. The ambassador and three other Americans were killed in a Sept. 11 attack.

In the Central African Republic, rebels have seized at least 10 northern towns. On Saturday they continued their advance, seizing the city of Sibut, 114 miles from Bangui.

The news of the rebels taking Sibut comes as regional African countries have agreed to send more forces to support the government of President Francois Bozize.

Talks between the rebels and the Bozize government are planned to start this week in Gabon.

Representatives from the 10-nation Economic Community of Central African States agreed Friday at a meeting in Gabon to send forces to the Central African Republic.