* Central African PM says dozens killed, hundreds injured in Bangui
* Urges immediate deployment of French troops, African peacekeepers
* Says Central Africa needs 670 million euros emergency foreign aid
* U.N. Security Council authorizes use of force to protect civilians
* Hollande says to double French contingent "within days or hours" (Adds details, quotes)
By Daniel Flynn
PARIS, Dec 5 (Reuters) - Central African Republic Prime Minister Nicolas Tiangaye appealed to France and African nations on Thursday to take immediate action to stem worsening sectarian violence, after the U.N. authorized the use of force to protect civilians.
More than 100 people were killed in the riverside capital Bangui on Thursday in fighting between the Seleka movement which seized power in March and gunmen loyal to former president Francois Bozize, witnesses said.
The landlocked nation of 4.6 million people was plunged into chaos when the mostly Muslim Seleka fighters toppled Bozize, unleashing a wave of sectarian violence which interim President Michel Djotodia - Seleka's leader - has been powerless to stop.
"The situation is extremely serious and worrying. There are serious violations of human rights: massacres, rapes and pillaging on a huge scale," he told Reuters in an interview. "This must prick the world's conscience and bring the whole international community to act."
He spoke moments before the U.N. Security Council unanimously authorized French and a regional African peacekeeping mission, known as MISCA, to use force to protect civilians.
"What I demand of the international community ... is to act immediately, that is to say deploy the MISCA and French forces to stabilise the situation," Tiangaye said.
French President Francois Hollande said on Thursday France would double its 600-strong troop contingent in Central African Republic "within days, or even within hours."
The U.N. resolution imposed an arms embargo on the country and asked the United Nations to prepare for a possible peacekeeping mission - something Tiangaye said his government would support.
"The situation has worsened a lot with the fighting in Bangui this morning," Tiangaye said, noting dozens had been killed and hundreds injured according to a provisional toll.
"This was not just inter-religious fighting: it was a fight to seize power. Its targets were political and military," Tiangaye said. "It has been established beyond doubt that elements close to Bozize were behind this (attempted) coup."
NEED FOR FINANCIAL AID
In addition to restoring security to his country, Tiangaye said he would ask Hollande, U.N. Secretary-General Ban Ki-moon and African leaders at a summit in Paris for emergency financial support for his government.
He said a donors conference would be organised in the first quarter of next year with the aim of raising 670 million euros needed to keep the state functioning, with the aim of organising elections before February 2015.
"We also need massive humanitarian aid from the international community," Tiangaye said, noting much of the rural population had fled violence to live in the bush, abandoning their farmlands. "There is a risk of famine."
Tiangaye also promised that those responsible for human rights abuses would face justice, both Seleka fighters and the Christian militias, known as anti-balaka.
"The authors of these crimes will be punished, be it by Central African justice or international justice," he said. "It saddens me to see these innocent victims - women and children - so I call on the Central African people to stop before committing a terrible historical error." (Additional reporting by John Irish; Editing by Mark John and Janet Lawrence)