The leader of Ivory Coast's main opposition party on Friday called for an "inclusive, transparent and credible" presidential election, although he is barred from standing due to a dispute over his nationality.

The west African country must show that it has reached "a sufficient level of political maturity to stop excluding presidential candidates", Tidjane Thiam said in an interview with AFP in Brussels.

Thiam resigned as leader of the Democratic Party of Ivory Coast (PDCI) on Monday and was re-elected to the post two days later in a vote where he was the only candidate.

A legal dispute over his nationality prompted his resignation in order to stand again and win re-election.

But the move has not resolved the question of his eligibility to run for president of Ivory Coast in the October 25 election. 

Three other opposition figures have also been excluded from the presidential race due to convictions, including former president Laurent Gbagbo.

"The essential thing is for Ivory Coast to hold an inclusive, transparent and credible election, and to show that it is capable of a peaceful transfer of power, as Senegal and Ghana have done," Thiam said.

The 62-year-old, who has been outside the country for nearly two months, was struck off the electoral list by an Abidjan court last month.

The court said Thiam lost his Ivorian nationality when he acquired French citizenship in 1987, basing its ruling on a 1961 law.

"That law is obsolete, it has never been applied to anyone in 64 years, and they’ve used it to erase me from the electoral list," said Thiam, a great-nephew of Ivory Coast's founding president Felix Houphouet-Boigny.

Thiam, who was born in Ivory Coast, renounced his French nationality in March to enable his run for the top job.

The authorities have consistently denied political interference in the election process, insisting that such decisions rest with an independent judiciary.

Thiam was in Brussels to attend a protest by Ivorian opposition supporters outside European Union institutions.

He said he had no plans to return home yet, citing uncertainty over the status of his identity documents.

"We asked for a nationality certificate from the justice ministry 10 days ago and we're still waiting... You need valid papers to travel, that's the decision of the authorities," he said.

According to Thiam, his national status -- whether single or dual citizenship –- remains unclear. "I was told I'm Ivorian again, but through a mechanism that nobody understands. 

"Some accuse me of having fraudulently regained Ivorian nationality."

Ivorian authorities insist that only the courts can change the electoral list now.

President Alassane Ouattara, 83, who has been in office since 2011, has yet to be nominated by his party but has indicated his desire to "continue to serve the country."