Central African rebels seized a town near the border with Chad on Wednesday, a day after Chadian troops entered the country on Bangui's request to help the army contain the rebel offensive.
According to sources on both sides, rebels from the Seleka rebel coalition captured the town of Kabo, near the Central African Republic's northern border with Chad, and were pressing on southwards.
“The attackers have cut all communications with Kabo... which they now control,” an official in the regular army told AFP on condition of anonymity.
Seleka commander Djouma Narkoyo also said his men controlled Kabo and were advancing on Batafango, further south.
The rebels, who threatened to overthrow President Francois Bozize, are still a long away from the capital Bangui, which lies more than 320 kilometres further south, on the southern border with the Democratic Republic of Congo.
But they have made extensive gains further east, defeating regular forces to seize a town called Ndele and then covering 150 miles to take control of Bria, a key diamond mining hub in the centre of the country.
Bozize, who seized power in a 2003 coup and has been toying with the idea of amending the constitution to seek a third mandate in 2016, invited Chadian troops across the border to help him stop the rebels.
Heavily-armed Chadian soldiers arrived on Tuesday in Kaga Bandoro, south-east of Batafango, and linked up with Central African forces.
“We are not afraid of the Chadians and we are determined to fight until the bitter end,” he told AFP by phone.
The Seleka coalition accuses Bozize of failing to abide by the terms of several peace deals reached with rebel factions between 2007 and 2011.
Members of ex-rebel group that had been integrated into the army as part of the agreements argue that the government failed to make good on its promise to lift them out of poverty.
The Central African Republic has been rocked by rebellions and coups since the fall in 1979 of military dictator Jean-Bedel Bokassa, who for almost three years reigned as emperor.
Bozize has never fully controlled the north and experts say the latest rebel offensive is a real threat to his regime.