Central African Republic capital under lockdown
The capital of the Central African Republic is under a night-time curfew after days of intense fighting between Christian and Muslim groups.
Fierce clashes between the two groups erupted after the killing of a Muslim taxi driver in Bangui on Saturday.
At least 36 people have died in the violence, and the UN says it has forced at least 10,000 people to flee.
A UN spokesman said the country may be returning to a state of violence unseen since conflict erupted two years ago.
"We fear that the violence we're seeing in Bangui is a return to the dark days of late 2013 and 2014, when thousands were killed and tens of thousands had to flee their homes," said Leo Hobbs, a spokesman for the UN's refugee agency.
The CAR has been wracked by violence since a mainly Muslim rebel group, the Seleka, seized power in March 2013.
The Seleka group was then ousted, sparking a wave of violent reprisals against the Muslim population, thousands of whom fled their homes.
Interior Minister Modibo Bachir Walidou told the BBC that the government remained in control but that the situation remained volatile.
Interim President Catherine Samba Panza returned from the UN General Assembly on Tuesday, and told the BBC that elections postponed for October would now be cancelled.
She accused "former dignitaries" of fomenting violence, singling out former president Francois Bozize.
Mr Bozize has criticised the decision to bar him from standing for election, saying: "Democracy was murdered in front of everyone in Central African Republic."