By Paul-Marin Ngoupana

BANGUI (Reuters) - A rebel column advanced on the capital of Central African Republic from the northwest on Saturday, attacking the town of Bossembele and opening a second front for government forces already battling insurgents northeast of Bangui.

A spokesman for the Seleka rebel coalition, which accuses President Francois Bozize of breaking a January peace agreement to integrate its fighters into the army, said its forces had seized control of Bossembele, 160 km (100 miles) northwest of Bangui.

Seleka spokesman Eric Massi said a second column was around 30 km (20 miles) from the capital to the northeast.

Local residents reported fierce fighting in Bossembele, which is home to a major military barracks, and at least one said rebels had captured the town. It was not immediately possible to confirm this with government officials.

"We have taken Bossembele," Massi said by telephone from Paris. "We are now 100 km (60 miles) from Bangui on this front."

Seleka, a loose umbrella group of insurgents, fought its way to the gates of the capital last year after accusing Bozize of failing to honor an earlier peace deal to give its fighters cash and jobs in exchange for laying down their arms.

It now says it has lost faith in Bozize, who seized power in the former French colony in a 2003 coup, and will topple him.

The violence is the latest in a series of rebel incursions, clashes and coups that have plagued the landlocked nation in the heart of Africa since its independence in 1960.

Residents in Bossembele reported gun battles between rebels and government forces, particularly around the military barracks on the southern route from the town.

"The town has fallen to the rebels," said Jean-Claude Sambia. "They control the town now and are everywhere."

The Seleka column had advanced southwards a day after capturing Bozize's hometown of Bossangoa, a major garrison town 300 km northwest of Bangui.

In the riverside capital, shops reopened and traffic returned to the streets after news on Friday of another rebel column less than 75 km to the northeast had sown panic.

FIGHTING TO NORTHEAST

State radio had announced late on Friday that South Africa would send more troops after President Francois Bozize met with his South African counterpart Jacob Zuma on Friday in Pretoria. South Africa's Defence Ministry was not available for comment.

Bozize hurriedly returned to Bangui later on Friday where officials said he was directly military operations from the presidential palace.

The violence is the latest in a series of rebel incursions, clashes and coups that have plagued the landlocked nation in the heart of Africa since its independence in 1960.

CAR remains among the least developed countries in the world despite rich deposits of gold, diamonds and uranium.

Government spokesman Crepin Mboli-Goumba said government forces, which deployed an attack helicopter on Friday, had pushed the rebel column to the northeast back beyond the town of Damara, some 75 km (50 miles) from Bangui on the main R2 road.

"The Central African army is fighting the rebels between Damara and Sibut since this morning," he said. Sibut, an important transportation hub, lies some 180 km (120 miles) from the capital.

Massi, however, said Seleka fighters had advanced from Damara and were now only 30 km from Bangui to the northeast.

"It is true that we lost ground after the helicopter attack yesterday but we got under way again this morning and we are at the gates of Bangui," he said.

Mboli-Goumba said the South African troops had not taken part in the fighting and remained stationed in Bangui.

"We are open to negotiations. The door is still open provided the rebels' demands are reasonable," said Mboli-Goumba.

(Additional reporting by Ange Aboa in Abidjan; Writing by Daniel Flynn; Editing by Michael Roddy)