There is a mood of deep anxiety in the capital of the Central African Republic, Bangui, as rebels advance towards the city, a UN envoy has said.

Margaret Vogt told the BBC she had seen that residents of Bangui were "petrified as to what could happen".

The UN is now evacuating its non-essential staff from the country, while the US urged its nationals to leave.

France has ordered tighter security of its embassy in Bangui after it was attacked by protesters.