A court on Monday ordered Nigeria's electoral body to produce evidence supporting its declaration of Umaru Yar'Adua as president-elect after a poll labeled "not credible" by international observers. Last month's elections for a new president, state governors and legislators were billed as the first fully democratic transition in Nigeria, Africa's most populous country and top oil producer.

Instead they were condemned as a "charade" by domestic observers and they have generated fierce controversy -- although few mass protests beyond the first few hours after disputed results were announced.

Opposition parties had applied to the tribunal to force the electoral body to produce ballots and other material backing up its announcement of a landslide for the ruling People's Democratic Party as a first step to overturning the result.

"The first applicant is permitted to inspect polling materials including results and other electoral materials used for the April 21 presidential elections," said Justice Rabiu Mohammed, granting a request by opposition candidate and vice president Atiku Abubakar.

The materials will be used by opposition candidates to support petitions which must be filed by May 23.

Analysts give little hope to opposition candidates seeking to overturn the presidential result, because evidence of rigging is hard to obtain and the declared margin of victory so wide.

But some candidates for state governorships, the National Assembly and state assemblies stand a good chance, they added.

European observers reported widespread fraud during the polls including ballot-stuffing, intimidation and falsification of results, and said the elections were "not credible".

Yar'Adua is due to be inaugurated on May 29, in what will be the first handover of power from one elected leader to another in a country scarred by three decades of military rule.

Calls for mass protests against the result, which saw Yar'Adua win with almost four times the votes of his nearest rival, have met with a muted response so far.

The Nigeria Labour Congress, an umbrella body of workers' unions, has said it would organize a two-day strike before the inauguration, but it has not set a date. The Nigerian Bar Association on Monday called on its members to boycott court duties on May 18.

REUTERS