By Ange Aboa

BANGUI (Reuters) - Rebel forces and international peacekeepers mopped up pockets of resistance on Wednesday in Central African Republic after a weekend coup but life in the capital was mostly returning to normal after three days of looting.

Up to 5,000 rebels swept into the riverside town on Sunday, killing at least 13 South African soldiers in intense fighting and forcing President Francois Bozize to flee in the latest conflict to destabilize the landlocked former French colony.

The Seleka rebel coalition struggled to stamp out the chaos that ensued and was forced to appeal to peacekeepers from neighboring central African states to help control gunmen looting houses, business, U.N. offices and even hospitals.

"Security is okay but it is not perfect. There are still some pockets of resistance," said a senior United Nations official, adding there were still the dregs of pro-Bozize militias.

"Arms were distributed to youth in certain neighborhoods by the outgoing president," the official said.

He said conditions were slowly improving in the sprawling capital, easing fears of a major humanitarian crisis.

"Things are starting to pick up," he told Reuters. "We need doctors and nurses to come back to work, and supplies of power and drugs. I hope it will only take a few days to sort out."

A senior source with the FOMAC regional peacekeeping force said 100 government troops were holed up at a military base at Berengo, 60 km from the capital, refusing to surrender to rebel forces.

"They don't want to fight, just surrender and go home to their families. We will organize their evacuation," said the source, who asked not to be identified.

Keeping his promise to honor a power-sharing deal signed in January, self-proclaimed president Michel Djotodia officially reappointed Nicolas Tiangaye, a civilian opposition figure, as prime minister tasked with leading a transitional government.

The United States, France and regional powers have insisted the rebels must honor the Libreville accord, signed in January in the Gabonese capital, which called for a transitional unity government till elections in 2016.

SECURITY BEGINNING TO IMPROVE

Businesses reopened and traffic took to the streets of Bangui. A Reuters correspondent in Bangui said markets were open on Wednesday but many lacked food.

Electricity, cut off since Saturday when rebels struck a hydroelectric power station in a nearby town, had been restored in most neighborhoods but there was still no running water in many parts of the city, he said.

"The security situation is beginning to improve," Jean-Pierre Sandou, a sergeant with the roughly 1,000-strong five-FOMAC force, patrolling the crumbling city of 600,000 people.

South African soldiers battled the rebels for hours but troops from the FOMAC force did not try to prevent their advance, which came a decade to the month after Bozize himself seized power in a coup.

France's troops in the country also refused to intervene, saying they would only protect French citizens, as Paris steps away from its traditional role as Africa's policeman.

The United Nations and the African Union condemned the takeover, which came after a collapse in the January peace deal signed after a previous rebel advance to the gates of the capital in December.

Central African Republic has rich deposits of gold, diamonds and uranium but it remains one of the world's least developed and most unstable nations.

(Writing and additional reporting by David Lewis; Editing by Michael Roddy)