Bangui (Central African Republic) (AFP) - More than 20 people have been killed and around 100 injured in clashes in the capital of the Central African Republic, a military doctor said Sunday.

The new toll was up from 10 people earlier confirmed killed and 38 wounded in the unrest on Saturday sparked by the murder of a motorcycle-taxi driver in the Muslim-majority PK-5 neighbourhood.

A military doctor, speaking to AFP on condition of anonymity, said the new toll was "still provisional", noting that rescuers would take advantage of a lull in the violence to look for other victims.

The central PK-5 neighbourhood was the epicentre of unprecedented killings between Christians and Muslims in Bangui in late 2013 and early 2014.

In the wake of the violence authorities on Sunday put the capital under a 6pm (1700 GMT) to 6am curfew.

"International forces as well as Central African security and defence forces have been instructed that the measure is to be strictly enforced," Prime Minister Mahamat Kamoun said on national radio.

A helicopter operated by international forces deployed in the impoverished landlocked nation was seen flying over Bangui on Sunday morning.

A few sporadic gunshots were heard overnight. Residents who fled their homes on Saturday, fearing new clashes, were beginning to return by morning, an AFP correspondent said.

The motorcycle taxi driver whose death sparked the latest violence was murdered on Saturday morning, residents said. The motive for the killing was unknown.

The country's transitional government condemned the "useless violence (which) comes as Central Africa in general and the city of Bangui in particular yearns for peace and security."

The former French colony descended into bloodshed after a 2013 coup ousted longtime leader Francois Bozize, and it remains prey to violence between Muslim Seleka rebels and Christian militias known as the "anti-balaka", or anti-machete.

Though the level of violence has fallen significantly since last year, the country still has high crime rates fuelled in part by easy access to weapons left over from the sectarian conflict.