Russia has warned that military intervention in Niger would lead to a "protracted confrontation" after regional bloc Ecowas said it would assemble a standby force.
West African nations have approved armed intervention in Niger "as soon as possible", the Ivory Coast president says, following a meeting to discuss the coup.
The six people who have been arrested in connection with the killing of Ecuadorian presidential candidate Fernando Villavicencio are Colombian, police say.
