The presidential palace was also hit in the helicopter attacks, witnesses said.

The strikes came as fighters backing Mr Gbagbo's rival Alassane Ouattara stepped up their attempts to take control of the main city, Abidjan.

Mr Gbagbo has refused to quit despite UN-approved results saying Mr Ouattara won an election last November.

In recent days, pro-Ouattara forces have launched a sustained assault, sweeping down from their northern strongholds to capture the rest of the country.

There are about 50 pro-Ouattara soldiers resting in the shade, including some wounded who have just come back from the battle for Abidjan. One soldier described the fighting as "hot".

A lot of troops have just left for what senior military commanders here are telling me is the final push for the city. A general emerged from a meeting at a makeshift headquarters at a half-built toll station and said the city would be in his control in "a matter of hours".

Pro-Ouattara commanders say they have now launched their final assault on the city and expect to take it in a matter of days.

Many residents in Abidjan, a city of five million people, are said to be trapped indoors without food, water or electricity.