Ouattara: Opponents say he is a national of Burkina Faso

The Supreme Court ruled on Thursday that the former prime minister was ineligible for the election because there were doubts about his nationality.

The French Government also condemned the court decision.

Mr Ouattara had been barred for similar reasons from standing in the 22 October presidential election, which led to widespread clashes between his supporters and those of his opponents, including the new Ivorian president, Laurent Gbagbo.

Resignation

Mr Eckhard said the UN secretary-general had said all along that only an election with the broadest possible participation would serve the cause of democracy and stability in Ivory Coast.

The RDR party said it was "no longer interested in the sham reconciliation process" launched by the new President Laurent Gbagbo after the ousting of military ruler General Robert Guei.

Gbagbo: Wife's candidacy questioned

The party's secretary-general, Henriette Diabate, announced on Friday the immediate resignation of all RDR members from the mediation committee for national reconciliation, which was set up last month.

The Supreme Court ruled on Thursday that Mr Ouattara's nationality certificate had been issued "without regard for mandatary legal procedures" and so he could not be granted Ivorian citizenship.

The ruling came as campaigns began for the parliamentary elections, billed as a key test for the current government, which took power after an uprising against the military regime.

Questions have also been raised about the candidacies of Simone Gbagbo - the wife of President Laurent Gbagbo - and Emile Constant Bombet of the former ruling Ivory Coast Democratic Party (PDCI).

The RDR and the PDCI boycotted last October's presidential elections after the two candidates were barred from the race.

Analysts say the exclusion of Mr Ouattara, the country's most prominent politician, could lead to further political and ethnic clashes.