France has sent extra extra troops to Ivory Coast and taken control of the airport in the main city, Abidjan.
Fighting continues in the city between forces loyal to Alassane Ouattara and the incumbent Laurent Gbagbo.
Mr Ouattara is recognised by the United Nations as the winner of a presidential election last November.
A pro-Gbagbo television station has called for people to mobilise against what it says is an occupation by France.
A French military spokesperson says an extra 300 soldiers have been sent, taking its total presence to 1400.
The airport had been secured by UN personnel and the French takeover allows it to reopen.
Mr Ouattara's forces are reported to be planning a further advance towards the presidential palace and have imposed a curfew on the city.