* Rebels control strategic points in Bangui - government officials
* Presidential advisor says Bozize has fled to Congo
* Leading Seleka member declares himself president
* Witness says at least nine South African soldiers killed
By Paul-Marin Ngoupana
BANGUI, March 24 (Reuters) - Rebels in Central African Republic seized the riverside capital Bangui in fierce fighting on Sunday, forcing President Francois Bozize to flee and sowing confusion over who rules the mineral-rich heart of Africa.
At least nine South African soldiers were killed trying to prevent the rebels from taking Bangui, a Reuters witness said, dealing a blow to Pretoria's attempt to stabilise the chaotic central African nation and assert its influence in the region.
The Seleka rebel coalition resumed hostilities on Thursday in the former French colony and quickly swept south to Bangui with the aim of ousting Bozize, whom it accused of breaking a January peace deal to integrate its fighters into the army.
"We have taken the presidential palace," Eric Massi, a Seleka spokesman, told Reuters by telephone early on Sunday.
Government officials confirmed the rebels had captured the city of more than 600,000 people, which lies on the banks of the Oubangi river bordering Democratic Republic of Congo.
The violence is the latest in a series of rebel incursions, clashes and coups that have plagued the landlocked nation - which has rich yet underexploited deposits of gold, diamonds and uranium - since independence from France in 1960.
Bozize rose to prominence in the military during the 1966-1979 rule of former dictator Jean-Bedel Bokassa, a self-styled emperor. Bozize seized power in a 2003 coup but his failure to make good on promises of power sharing after winning disputed 2011 polls led to the offensive by five rebel groups known as Seleka, which means "alliance" in the Sango language.
Seleka leader Michel Djotodia, named as deputy prime minister after January's peace deal, proclaimed himself interim president on Sunday, the movement's Secretary-General Justin Kombo told Reuters.
France's RFI radio said Djotodia had asked Prime Minister Nicolas Tiangaye to lead a government to the next elections, scheduled for three years' time. He also imposed a curfew in Bangui, where residents reported widespread pillaging.
"The looting is bad. Both the population and Seleka are involved," said one senior U.N. official in Bangui. "We are not sure who is in charge. I don't think it is clear yet."
France, which already had 250 soldiers in Central African Republic, has sent another 300 troops from Gabon since Friday to ensure the security of French citizens and diplomatic installations in Bangui, according to the defence ministry.
CALLS FOR SWIFT ELECTIONS
Chadian President Idriss Deby, a regional power broker, recognised in a statement on Sunday that Seleka controlled the country and ordered regional peacekeepers to help restore security to the capital.
Djotodia's announcement was rejected by some members of his own loose rebel coalition - several of whom are former rivals.
"We are not there to take power by force. We'll put in place a transitional authority of 18 months then go to elections," said Nelson Ndjadder, spokesman for Seleka's CPSK faction.
Martin Ziguele, a former prime minister and president of the civilian opposition MLPC, said he would support Djotodia as interim president provided the transition lasted only one year.
The African Union condemned the rebels' seizure of power, calling for "unified, decisive action" from its members and threatening the country with suspension from the body and Seleka's members with targeted sanctions.
The whereabouts of Bozize - who seized power in a 2003 coup backed by neighbouring Chad - were uncertain. A presidential advisor said he had crossed the river into Congo on Sunday morning as rebel forces headed for the presidential palace.
Congo's information minister said Bozize's wife and children - including his eldest son Francis, the former head of defence - were flown out of the Congolese border town of Zongo by the U.N. peacekeeping mission. But he said the ousted president was not among them: "Bozize is not in Democratic Republic of Congo."
French Foreign Minister Laurent Fabius confirmed Bozize had fled Bangui, but gave no details of his whereabouts. He appealed to France's 1,200 citizens in the country to remain calm and stay in their homes.
The city remained without electricity and water as night fell on Sunday after the Seleka forces - who had seized the nearby town of Boali with its electricity station - turned off the power a day earlier.
The International Committee of the Red Cross said the outages were hindering medical staff attempting to care for the many injured arriving at the city's hospitals.
France has only limited economic interests in the turbulent country. French nuclear giant Areva shuttered its Bakouma uranium project for two years in 2011 following a fall in uranium prices after the Fukushima disaster.
NINE SOUTH AFRICANS DEAD
Seleka's forces had fought their way to the northern suburbs of Bangui late on Saturday before an overnight lull in the fighting. Residents said heavy weapons fire erupted across the city around 8 a.m. (0700 GMT).
Seleka's Massi said the rebels had broken through a line of South African soldiers during their push into the city. Around 400 South African troops were deployed in the country as military trainers.
"I saw the bodies of six South African soldiers. They had all been shot," a Reuters witness said. Later, he saw three more bodies in burned-out South African military vehicles.
Regional peacekeeping sources said the South Africans had fought alongside the Central African Republic's army on Saturday to prevent rebels entering the capital.
South African army spokesman Brigadier-General Xolani Mabanga confirmed that the country's contingent in Bangui had sustained casualties when they came under attack on Saturday, but he declined to give further details.
A source with the United Nations in Bangui said the South Africans had asked for assistance from French forces to help them leave the country.
Several peacekeepers from the Central African regional force, including three Chadians, were also killed on Saturday, when a helicopter operated by Bozize's forces attacked them, Chad's presidency said in a statement.
Seleka's CPSK faction spokesman, Ndjadder, called upon fighters and the population to stay calm and avoid looting.
A Reuters witness, however, saw youths pillaging houses -including the residence of Bozize's son, Francis - in the northern part of the city.
Rebel fighters directed looters towards the houses of army officers but fired their rifles in the air to protect the homes of ordinary citizens, the witness said.
Seleka fought its way to the gates of Bangui last year after accusing Bozize of violating an earlier peace deal to give its fighters cash and jobs in exchange for laying down their arms.