Rebels in the Central African Republic advanced on the capital Friday claiming they were at "the gates of Bangui", after the collapse of a two-month-old peace deal.
Troops from the Seleka rebel coalition shot their way through the key Damara checkpoint some 75 kilometres (50 miles) north of the capital, said a source with the Multinational Force of Central Africa (FOMAC), a regional stabilisation mission which was manning the roadblock.
"The rebels stormed the checkpoint and passed through.... There were shots but no wounded," said the source on condition of anonymity. "They are on the road to Bangui. We're on the highest alert."
Colonel Djouma Narkoyo, a rebel chief contacted by AFP by telephone from Libreville, said: "We are at the gates of Bangui.
"I cannot tell you where, it is a military secret as well as our numbers, but Damara is behind us."
A French foreign ministry statement confirmed that the rebels were "only a few kilometres" from Bangui. Ministry spokesman Philippe Lalliot called for "all parties to show restraint and respect the civilian populations".
Narkoyo said "the last barrier is the South Africans", referring to South African troops on a stabilisation mission in the capital.
A South African helicopter had overflown their position, he said.
"They fired on us below but there were no victims" from the attack. His report could not be independently confirmed.
The government denied the rebels had passed Damara in a statement on national radio, and urged residents of Bangui to not "give in to panic".
As reports of a rebel advance spread quickly in the capital, the streets emptied as people rushed home or tried to flee the city.
"Everyone is going home," a shopkeeper said in a telephone interview. "Students have been released from classes. We're waiting. We're worried."
One boat operator at the city's port said hundreds of people were trying to cross the Ubangi river to seek shelter in neighbouring Democratic Republic of Congo.
"The indications that we have about Central Africa are worrying," French Foreign Minister Laurent Fabius said, adding France would do what was necessary to ensure its nationals were protected.
The ministry said it had told around 1,000 French nationals who live in the former French colony to be vigilant.
-- Bozize in talks with Zuma --
President Francois Bozize met South African President Jacob Zuma in Pretoria on Friday, a government website there reported, but there were no details of their talks.
In January, when the rebels were sweeping south towards the capital, Zuma sent 400 South African troops to the country to back efforts to stabilise the situation. But they were only due to stay until the end of March.
The latest rebel offensive came two days after Seleka announced it would resume hostilities after a deadline for the government to meet its demands under a January 11 peace deal expired.
Seleka, an alliance of three rebel movements, first launched an offensive on December 10 in the north of the chronically unstable country.
Facing little resistance from an ill-trained and ill-equipped army, the rebel forces -- who accused Bozize of not respecting earlier peace deals -- seized a string of key towns. They defied UN Security Council calls to stop, before halting within striking distance of Bangui.
Under the January peace deal, an opposition member, Nicolas Tiangaye, became head of a national unity government that was to carry out reforms before national elections next year.
But the deal remained fragile, with the rebels threatening to pull out if their demands were not met. They wanted the release of political prisoners and for foreign soldiers to leave the country.
Over the weekend, the rebels detained five ministers from the new government to lend force to their demands for concessions from the authorities.
Bozize then offered to release political prisoners and end a night-time curfew but Seleka said that was not enough.
UN leader Ban Ki-Moon called on Seleka to "immediately halt its military offensive" and for all sides to stick to the January 11 peace accord, his spokesman Martin Nesirky said.
The UN Security Council said the new troubles "jeopardise the precarious stability" of the country.
Central African Republic, a landlocked nation of 4.4 million people, has been plagued by instability since its independence in 1960. Bozize seized power in a 2003 coup.