He is accused of fraud and the use of forged documents. Mr Ouattara has been disqualified from challenging President Henri Konan Bedie in elections next year on the grounds that his father was not born in Ivory Coast.

Mr Ouattara has denied accusations that he falsified his Ivorian identity papers.

Alassane Ouattara is accused of falsifying identity

The BBC's Mark Doyle says Ivory Coast's key Western backers have condemned the moves against Mr Ouattara, implying that the nationality issue is really just a pretext for an old-fashioned crackdown on political opponents.

Mr Ouattara's disqualification has sparked political unrest which has seen the imprisonment of his leading supporters.

At least 11 leading members of his Republican Rally party - including the deputy leader, Henriette Diabate - were sentenced in November to two years in jail, after being accused of of public order offences committed by their supporters.

President Bedie has banned demonstrations

Earlier this month, police in the Ivorian capital, Abidjan, used teargas to disperse a group of women who defied a government ban on street protests and demonstrated for the release of jailed opposition leaders.

The oppostion has denounced the government ban as unconstitutional.

President Bedie said it was intended to preserve public order and that he would not tolerate those who sought to make Ivory Coast ungovernable.

Mr Ouattara said the government's crackdown was designed to stifle the opposition and prevent a democratic change of power.