It comes after France boosted the number of its troops in the country and said it was in control of the airport at Abidjan, the country’s largest city.
Fierce fighting was continuing between troops loyal to incumbent leader Laurent Gbagbo and the president-elect, Alassane Ouattara.
Henry Gray, from international medical and humanitarian aid organisation Medecins Sans Frontieres (MSF), told Sky News Abidjan was in lockdown.
« There’s heavy fighting in some areas of the city and looting in other areas, » he said.
« We’re hearing the sound of heavy weapons fairly regularly and small arms fire as well.
« We are running out of food, we don’t have water at our office at the moment – but we’re probably in a better shape than a lot of people [in Abidjan]. »
The UN mission in Ivory Coast has started withdrawing « essential » employees after frequent attacks on its office in Abidjan.
Non-essential staff were evacuated several months ago.
Reports said those being evacuated were being taken by helicopter from the UN base to the airport.
Ivory Coast – also known Cote d’Ivoire – has been wracked by bloody violence since Mr Gbagbo refused to leave office after losing an election last November.
Mr Ouattara is recognised as having won the poll by the international community and has backed his claim to power with deadly force.
The UN said on Saturday more than 400 people have been killed in the violence so far – but aid agencies believe the number could be more than double that figure.
The Red Cross said at least 800 civilians were killed in a single battle during the ongoing struggle for control of Ivory Coast.
Over the past four months clashes between the two sides have claimed hundreds of lives, displaced at least a million people and turned Abidjan into a war zone.
Forces loyal to Mr Ouattara were gathered outside Abidjan on Sunday ready for an advance on the city, according to reports.
There was renewed tension in the city as an extra 300 French troops were sent in to boost the size of the Operation Licorne force, which now numbers 1,400 soldiers.
Both Britain and the US have called on Mr Gbagbo to step aside amid the widespread unrest.
« The path forward is clear… (Mr Gbagbo) must leave now so the conflict may end, » America’s Secretary of State Hillary Clinton said.
Foreign Secretary William Hague called for restraint in Ivory Coast and said alleged human rights abuses in the country’s largest city, Abidjan, must be investigated.
« I am gravely concerned by the violence in Cote d’Ivoire and deplore reports of loss of life, » he said in a statement.
« I call on all sides to exercise restraint, and condemn the looting and lawlessness reported in Abidjan.
« Laurent Gbagbo must heed the calls from the international community and step down at once to prevent further bloodshed. »
The 65-year-old Mr Gbagbo has not been seen since the uprising against him began.
Fighters supporting Mr Ouattara have claimed nearly 80% of the African nation in a bid to install him as president.
S: news.sky.com
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