Abidjan, Ivory Coast (CNN) -- Former Ivory Coast President Laurent Gbagbo was being transferred Tuesday to the International Criminal Court in The Hague, said his adviser, Toussaint Alain.
He was flown out of the northern city of Khorogo, where he had been under house arrest, on an airplane of the Ivorian government at about 6 p.m. Tuesday, Alain said.
Alain called it an illegal transfer. "The international court has taken an illegal action. This is a political decision rather than a decision of justice," Alain said.
The transfer was announced on national television Tuesday evening.
The action comes a week before parliamentary elections. Three political parties in an umbrella coalition (CNRD) with Gbagbo's Front Populaire Ivorien issued a statement saying they would boycott the elections as a result of Gbagbo's transfer.
Last month, the chief prosecutor for the International Criminal Court, Luis Moreno-Ocampo, arrived in Ivory Coast to meet with government and opposition leaders and began an inquiry into the West African nation's post-election violence.
In his application to the judges for authorization to investigate possible war crimes and crimes against humanity, Moreno-Ocampo cited sources who said at least 3,000 people were killed, 72 people disappeared and 520 others were subject to arbitrary arrest and detentions since the November 28, 2010, election that resulted in the violence.
Gbagbo, the incumbent, refused to cede power even though challenger, Alassane Ouattara, was internationally recognized as the winner. Months of bloodshed ensued. The political stalemate was settled by Gbagbo's capture in April by forces loyal to his rival, and he has been detained in the north of Ivory Coast. Gabgbo refused to accept the results of UN-certified elections.
Human Rights Watch issued a statement saying Gbagbo is "the first former head of state taken into custody by the ICC."
President Omar al-Bashir of Sudan and the late Libyan leader Moammar Gadhafi have also been subject to ICC arrest warrants, but Al-Bashir has not come into ICC custody, nor did Gadhafi, who was killed this year during Libya's revolution, Human Rights Watch said.
"The ICC is playing its part to show that even those at the highest levels of power cannot escape justice when implicated in grave crimes," Elise Keppler, senior international justice counsel at Human Rights Watch, said in a statement.
"This is a big day for the victims of (Ivory Coast's) horrific post-election violence," Keppler said. "That Laurent Gbagbo now has to answer to the court sends a strong message to Ivorian political and military leaders that no one should be above the law."
CNN's Michael Martinez contributed to this report.