ABIDJAN (AFP) - Ivory Coast's former first lady Simone Gbagbo went on trial Friday for "attempting to undermine the security of the state" in events leading to a bloody 2010-2011 crisis that left thousands dead.

Gbagbo, who has been held for three years and is also wanted by an international court for crimes against humanity, entered the Abidjan court where she is standing trial with 82 others, to cheers and applause from the public.

The 65-year-old wife of ex-president Laurent Gbagbo wore a yellow silk dress and tressed hair as she faced the judge, while outside riot police were deployed and officers body-searched people entering the law courts.

The trial is viewed as the biggest judicial challenge faced by the post-crisis government of the west African nation.

Nicknamed the "Iron Lady", Gbagbo is being tried for her role in events leading to months of post-election violence that left some 3,000 people dead and badly rattled the economy of the prosperous cocoa-producing nation.

Violence broke out in Ivory Coast in 2010 when Laurent Gbagbo refused to cede power to his rival Alassane Ouattara, who was declared the winner of a presidential poll.

Laurent Gbagbo himself has been held for three years in The Hague facing charges of crimes against humanity by the International Criminal Court (ICC). But Ivory Coast has repeatedly refused to hand his wife over to the ICC on the same charge.

The presidential couple were arrested April 11, 2011 after five months of fierce fighting after a final push by French forces against their residence.

Pictures at the time showed the once-powerful wife, a leading political figure accused of links with anti-Ouattara "death squads", haggard, fearful and unkempt, her usually stylish hair a mess.

Simone Gbagbo had been held under house arrest in Odienne in the northwest of the country since April 2011 but was transferred to the economic capital, Abidjan, on December 1 ahead of the trial.

Among those seated in the dock next to her, smiling for the cameras, was Gbagbo's last prime minister Gilbert Ake N'Gbo and Affi N'Guessan, head of the Ivorian Popular Front (FPI) party.

Proceedings Friday were expected to be limited to jury selection, with hearings beginning in earnest on January 5.

"This trial has been rushed through to obtain five million euros pledged by the EU as part of a programme to rehabilitate the Ivorian justice system," one defence lawyer said.