Bangui - Chadian troops entered the neighbouring Central African Republic (CAR) on Tuesday following an appeal from Bangui's president Francois Bozize after rebels seized a number of key towns, a CAR military official said.
A coalition of three rebel factions is threatening to overthrow the Bozize government, demanding respect for different peace accords signed between 2007 and 2011.
"Heavily armed elements of Chadian ground forces aboard 20 vehicles arrived in the middle of the afternoon at Kaga Bandoro where they joined elements of the Central African armed forces based there," the CAR official told AFP.
The intervention occurred after the rebels captured the diamond-mining and garrison town of Bria, 400km northeast of the capital.
Chadian President Idriss Deby Itno is a close ally of Bozize whom he helped when the high-ranking army officer seized power in 2003.
Chadian forces, who have successfully quelled rebellions in the east of their own country, had already been sent to CAR in November 2010 to drive out Convention of Patriots for Justice and Peace (CPJP) rebels from the north-eastern town of Birao.
The military official said Chadian forces were to "back up Central African armed forces in the counter-attack aimed at retaking towns that have fallen into the hands of the rebels".
Bozize was expected in Kaga Bandoro on Tuesday night before the allied troops would head for the "occupied areas", he added.
A coalition of rebel factions operating under the name of Seleka CPSK-CPJP-UFDR earlier Tuesday took Bria, ousted the underpaid, disorganised and badly equipped government forces and began looting its shops.
The attack came eight days after a UFDR fringe group attacked the towns of Ndele, Sam Ouandja and Ouadda.