BANGUI, Central African Republic: Rebels in the Central African Republic advanced on the capital Friday claiming they were at "the gates of Bangui", as they resumed an offensive in the mineral-rich country 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."

Later Friday a rebel chief, colonel Djouma Narkoyo, told AFP: "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."

Contacted by AFP by phone from Libreville, Narkoyo added:

"The last barrier is the South Africans," referring to South African troops on a stabilisation mission in the capital.

He also said that a South African helicopter had "overflown our position, they fired on us below but there were no victims" from the attack, which could not be independently confirmed.

Earlier a rebel spokesman called on the population to remain calm.

"We call on everyone, both civilians and the military, to remain calm ahead of our troops' arrival in Bangui, to avoid unnecessary fighting," rebel spokesman Eric Massi told AFP from Paris.

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".

Reports of a rebel advance spread quickly in the capital, whose streets emptied as people rushed home or tried to flee the city.

"Everyone is going home. Students have been released from classes. We're waiting. We're worried," a shopkeeper said in a telephone interview.

At the city's port, a boat-operator said "hundreds of people" were trying to cross the Ubangi river to seek shelter in neighbouring Democratic Republic of Congo.

French Foreign Minister Laurent Fabius Friday expressed concerns about the situation in the former French colony.

"The indications that we have about Central Africa are worrying," he said, adding that in any case France would do what was necessary to ensure that "French nationals are protected."

The rebel attacks 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 President Francois Bozize of not abiding by earlier peace deals -- seized a string of key towns, defying 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.

The rebels at the weekend detained five ministers from the new government, including members of the rebel coalition, to back their demands for concessions from the authorities.

Bozize then offered to release political prisoners and end a night-time curfew in a bid to head off a showdown with the rebels, but Seleka said this was not enough.

The UN Security Council on Wednesday expressed "strong concern" over mounting new tensions in the vast African nation.

Council members also "condemned the attacks conducted recently by rebels from the Seleka coalition, in particular in Bangassou and the surrounding region, and the threat of a resumption of hostilities."

The Security Council said the new troubles "jeopardise the precarious stability" of Central African Republic, a landlocked nation of 4.4 million people plagued by instability since its independence in 1960, and where Bozize seized power in a 2003 coup.