Rebels claim to have captured a second town in the Central African Republic (CAR) during a two-week long offensive.
They told a BBC reporter by satellite telephone that they had taken the isolated settlement of Ouadda-Djalle, 200km west of the border with Sudan.
A government spokesman confirmed rebel activity but not the town's capture.
The UFDR rebels say they are fighting against corruption and mismanagement under President Francois Bozize, who seized power in a 2003 coup.
The towns of Ouadda-Djalle and Birao, which fell two weeks ago, are near eastern Chad and Sudan's western Darfur region which have been plagued by violence and insecurity in recent years.
The CAR government says the rebels are operating from Darfur with the support of the Sudanese authorities.
It has called for French military help to put down the rebellion.
'Poised to advance'
"We captured this town in the early hours of the morning this Friday after [a] fierce battle with the regular army," rebel spokesman Abakar Saboune told the BBC.
Refugees from CAR fled fighting into Chad earlier this year
He gave no casualty figures, but said that their forces - now 750km north of the capital, Bangui - were poised to capture another two towns.
After the capture of Birao, the rebels called for a national conference to discuss power-sharing, but Mr Saboune said the government has not responded.
"There is no alternative, we have to continue with the military option as President Bozize and his regime are opposed to dialogue," he said.
Security in the north has deteriorated in the past year, due to an increase in robberies and the emergence of the rebels seeking to overthrow President Bozize, who won elections last year.
The BBC's Joseph Benamse in Bangui says some of the rebels fought alongside Mr Bozize when he ousted Ange-Felix Patasse from power three years ago.
But they fell out with him when they were not given the pay they were promised.