France says its UN-backed military operation is underway in the Central African Republic, the day after some of the worst violence in the latest crisis.

The Defence Minister told French radio that troop reinforcements had arrived in the capital Bangui to bolster the forces already there – who will number 1,200 in the coming days.

On Thursday militias loyal to the ousted president attacked the capital where mainly Muslim former rebels took control in March, plunging the country into chaos that has seen tit-for-tat sectarian violence with the Christian majority.

Witnesses said more than 100 people were killed in Thursday’s fighting, before nightfall saw a relative calm.

Many were clubbed or hacked to death. Dozens of wounded were treated in hospital, including women and children.

The head of one aid team, MSF-Holland, said the true number of victims was unknown as it was impossible to venture out.

Many local defence groups have sprung up in response to abuses carried out by the former rebels.

President Hollande has vowed that the French operation will be limited in time with the aim of handing over to African forces.

The UN resolution gives the mission a mandate to protect civilians and restore order.