"Armed non-governmental groups in northern Chad have moved south and appear to be heading toward N'Djamena. Due to their growing proximity to N'Djamena, and the possibility for violence in the city, non-essential US government employees have been ordered to leave Chad by commercial airline. US citizens in Chad wishing to depart should take advantage of commercial flights", the statement says.
The US Embassy warned that the government of Chad could impose travel restrictions and block communication channels, and advised against travel within the country outside N'Djamena.
On Saturday, Chad's Army said it had "completely destroyed" a column of rebels that attacked the country on the day of the presidential election last week.
According to an AFP journalist, four tanks and several soldiers were deployed at the northern entrance of N'Djamena on Saturday evening, where military vehicles continued to drive towards the fighting.
A week ago, members of the Libya-based rebel group Force for Change and Concord in Chad (FACT), claimed to have seized garrisons near Chad's northern borders with Niger and Libya "without resistance".
Chad is located in the Sahel, notorious for terrorist activity and illegal migration. In 2014, France launched Operation Barkhane in the Sahel. It is being held jointly with the military forces of the G5 Sahel bloc that includes Mali, Burkina Faso, Chad, Niger, and Mauritania.