(CNN) -- Jean-Pierre Bemba Gombo, a former politician and militia leader, went on trial Monday in The Hague, Netherlands, accused of crimes against humanity and war crimes including murder, rape and pillaging.
"Jean-Pierre Bemba used an entire army as a weapon to rape, pillage and kill civilians the Central African Republic," International Criminal Court prosecutor Luis Moreno-Ocampo said as the long-awaited trial began.
"Today, he is brought to account for deliberately failing to prevent, repress or punish mass atrocities committed by his men" in the central African nation, he said.
Bemba, a former vice president in the Democratic Republic of Congo, is accused of leading his militia in attacks on civilians in the Central African Republic for almost five months, according to the International Federation for Human Rights.
Under his leadership, his Movement for the Liberation of Congo (MLC) allegedly murdered, raped and pillaged in the neighboring country between October 2002 and March 2003, the court said.
His defense team says the Central African Republic's government was accountable for the actions of the MLC.
Bemba sat with his arms folded across his chest as proceedings began, his chin slightly raised. His lawyer confirmed that Bemba understood the charges against him and his rights in court, including the right to remain silent or to enter a plea.
Last month, the International Criminal Court (ICC) turned down an appeal by Bemba and cleared the way for the trial.
Bemba's defense had challenged his case's admissibility on the grounds that the Central African Republic -- the country the alleged crimes occurred in -- investigated the case and made a "decision not to prosecute."
The ICC decided that the Central African Republic's action does not prohibit the case from being tried.
The British Foreign Office welcomed the beginning of the trial.
"I am pleased that the very serious allegations against Jean-Pierre Bemba Gombo will be fully investigated in an independent and fair trial," Henry Bellingham, the British minister for Africa, said in a statement.
"I also welcome the role that the victims of the crimes committed in Central African Republic will be able to play in the trial proceedings," he said.