Libreville - The dispute over Gabon's presidential election intensified Thursday as opposition candidate Jean Ping mounted a legal challenge, accusing the incumbent leader of fraud.The filing at the constitutional court was lodged by the Thursday deadline, according to a Ping lawyer, Jean Remy Bantsantsa.Ping, who seeks to unseat the family that has ruled this oil-rich Central African country for more than four decades, already has publicly declared himself the winner.Official election results said incumbent President Ali Bongo Ondimba won the August 27 vote by less than 2 percentage points. There is no provision for a runoff in Gabon.Gabon's UN Ambassador Michael Moussa-Adamo told The Associated Press that there may be a government announcement Friday about the constitutional court.He accused Ping of trying to rig the election and said the government has a confession from someone who allegedly helped his party hack the results."We have mountains of evidence of tampering from neighboring countries" to help Ping "steal the election," Moussa-Adamo said. "It's covert and documented."The EU observer commission has said that in addition to not having full access to all districts within Bongo's stronghold Haut-Ogooue province, voter turnout there appeared inflated.According to the country's electoral commission, the province saw a 99.93% turnout, with 95% voting in favor of Bongo.The EU noted that would mean only 47 people in the province would not have voted.Other provinces showed a 48% voter turnout on average, the EU said.Moussa-Adamo said the EU never said the elections weren't free and fair and "there's a lot of questions" about why it raised the "abnormalities" now. He noted that in some counties the opponents had over 100% voting "and nobody is questioning them."Fiery protests erupted after the results were announced last week. The opposition maintains as many as 100 people have died in the violence, while the government toll remains at three dead.France's prime minister has suggested a recount, and the United States and France have urged the government to publish results by individual polling stations. Gabon's justice minister has resigned over the government's refusal to recount the ballotsBongo came to power in 2009 after the death of his father, who had ruled Gabon since the 1960s.