Libreville - Gabon's leading opposition figure and former AU head was charged on Thursday with imprisoning and torturing people who attacked his home, risking up to 10 years in prison and possible elimination from the 2016 presidential election.Jean Ping, 72, a former head of the African Union, was charged with the illegal imprisonment, inhuman treatment and torture of some of the people who threw rocks at his residence on Monday, state prosecutor Sidonie Ouwe said.Ping, the head of an opposition coalition, said on Monday that his house had been attacked by at least 200 people, one armed with a poisoned knife, sent by an adviser to President Ali Bongo. The government denied the accusation."Nothing justifies the barbarism... of this statesman who ordered the arrest of the young men and took them to his compound. Degrading and humiliating treatment was then inflicted on them including physical torture," Owue told a news conference.Ping, who had not been taken into custody, was not immediately available to comment on the charges on Thursday.An erstwhile ally of former president Omar Bongo, the current president's father, Ping has helped lead protests in recent weeks over a range of grievances and trade union disputes including one in December where a demonstrator was killed.The protests caused a temporary reduction in Gabon's 230 000 barrels per day output of crude oil. The country is one of sub-Saharan Africa's top oil producers, but about a third of the population of 1.5 million people live in poverty.Ali Bongo won a disputed election in the former French colony in 2009 following the death of his long-ruling father.