The government of Ivory Coast has welcomed a decision by the International Criminal Court to investigate the killings that followed last November's election.
At least 3000 people are estimated to have been killed after then-president Laurent Ggagbo refused to admit he had lost to Alassane Ouattara.
Mr Ouattara finally took power in April.
The BBC reports forces loyal to both men have been accused of committing atrocities.
Mr Gbagbo is being held under house arrest and has been charged with looting, armed robbery and embezzlement.
The election was intended to reunify the country, after a civil war in 2002. However, it is deeply divided along ethnic, religious and economic lines.