Ivory Coast's highest court has begun the trial of former first lady Simone Gbagbo for crimes against humanity and war crimes.

She appeared at the Abidjan Justice Court on Tuesday. The prosecution says she participated in a committee that planned and organized abuses against supporters of her husband's opponent after the 2010 election.

More than 3,000 people were killed after ex-President Laurent Gbagbo refused to accept defeat to now President Alassane Ouattara.

Simone Gbagbo has been in custody since April 2011. She has been indicted by the International Criminal Court in The Hague, Netherlands, for crimes against humanity, but Ivory Coast has refused to transfer her. The former president's ICC trial began in January.

Human rights groups have criticized Ivory Coast for conducting an incomplete investigation into her role and a breach of criminal procedure.