Paris - President Ali Bongo Ondimba of Gabon should take a DNA test to prove his parentage and eligibility to run for re-election later this month, a rival candidate said.Bongo faced allegations that he is not Gabonese, but Nigerian, and that he was adopted by his father Omar, who was president from 1967 until his death in 2009."We are faced with a candidate who has no right to be a candidate. We are witnessing a forced transition and a violation of our constitution," said Leon Paul Ngoulakia, one of 14 people challenging Bongo in the August 27 election.Ngoulakia is a cousin of Bongo's and until recently was one of his closest aides."Ali Bongo has produced at least four birth certificates, all seemingly fake. How come none of our institutions are able to prove his nationality and parentage," Ngoulakia told AFP during a visit to Paris."Why doesn't he simply submit to a DNA test to end all this debate? The people of Gabon are tired of this affair and want to hear other debates that are more important to our country's future," he said.On July 25, the constitutional court rejected an appeal against the eligibility of Bongo, who came to power in a disputed election following his father's death."The legal battle is not over. Procedures are continuing, the law must be followed all the way," insisted Ngoulakia.He said that Gabonese authorities had prevented opposition candidates holding public meetings and used tear gas in demonstrations."Conditions for a peaceful and transparent election are not in place," he said.Bongo himself said as much, claiming in an interview with Jeune Afrique magazine that his opponents had a strategy of stoking unrest with their persistent claims of his ineligibility.