Ivory Coast's government has started to exhume the mass graves of people killed in the violence that hit the country after the disputed 2010 election.Justice Minister Gnenema Coulibaly observed a moment of silence as a grave on the grounds of a mosque in the main city, Abidjan, was dug up.More than 3,000 people died after Laurent Gbagbo refused to cede power to current President Alassane Ouattara.The conflict ended after French-backed forces captured him in April 2011.Mr Gbagbo was handed over to the International Criminal Court. Judges are still to decide whether to put him on trial over the post-poll violence.He insists he is innocent, saying he always stood for democracy.'Dangerous legacy'The bodies exhumed were believed to be those four men aged 17 to 35 who were killed while defending the mosque against militants allied with Mr Gbagbo, reports the BBC's Tamasin Ford from Abidjan.The government intends to exhume 57 mass graves across the country, saying the recovery of bodies was a step towards achieving justice and reconciliation, she says.But New York-based pressure group Human Rights Watch (HRW) says the government has so far failed to charge any of Mr Ouattara's supporters over the violence, fuelling concerns about "victor's justice".More than 150 supporters of Mr Gbagbo have so far been charged over the conflict, it said in a report on Thursday."President Ouattara's expressed support for impartial justice rings hollow without more concrete action to bring justice for victims of crimes committed by pro-government forces," said HRW's Param-Preet Singh.If Ivory Coast "is going to break from its dangerous legacy in which people close to the government are beyond the reach of the law, it needs credible prosecutions of those responsible for crimes on both sides of the post-election conflict", he said.Ivory Coast's military prosecutor Ange Kessi Kouame told BBC Focus on Africa that he carried out investigations impartially."I prosecute if you make a crime, and I don't consider whether you are pro this camp or another," he said.