The war crimes trial begins Monday of the most senior political figure in the custody of the International Criminal Court, a former vice president of Congo who is being held to account for mass rape and murder of civilians by his followers in the neighboring Central African Republic.

The trial is only the third to get under way at the court that began work in 2002 and is the first to focus on so-called command responsibility — charging a military leader for crimes committed by his troops — and on the use of widespread rape as a weapon of war.

Prosecutors say Jean-Pierre Bemba allowed his personal militia, the Movement for the Liberation of Congo, to run amok in Central African Republic in 2002 and 2003 after the country's then-president, Ange-Feliz Patasse, asked for its help in an ultimately unsuccessful fight against rebels led by the country's former army chief of staff, Francois Bozize.

Calling them "neglected (victims) in a neglected country," prosecutor Luis Moreno Ocampo said the trial would shine a spotlight on the plight of girls, women and men raped in Central African Republic.

"International justice is forcing the world to pay attention to the victims of these atrocities," he said.

Prosecutors say Bemba's troops aimed to terrorize civilians into not supporting Bozize's rebels.

"He chose rape as his method," deputy prosecutor Fatou Bensouda told judges at a preliminary hearing.

Bensouda cited one unidentified witness, who said three of Bemba's men burst into his home firing their weapons, forced him to his knees as his family watched, then sodomized him for four hours. "In front of my eyes they abused my wife," she quoted the witness as saying. "After they finished with my wife, they came for my kids."

Prosecutors will call up to 40 witnesses at the trial and more than a dozen are victims of rapes. They expect to take around six months to present their evidence.

Bemba's lawyers say he had no command of his troops once they crossed the Oubangui River into Patasse's country and say he tried to investigate and prosecute officers responsible for atrocities.

In written arguments to the court, they say 48-year-old Bemba "strenuously denies a breach of command responsibility."

Activists hope the trial will send a message to fighters and their commanders around the world that using rape as a weapon will be punished.

Brigid Inder, executive director of Women's Initiatives for Gender Justice, said the trial should show women "that crimes of sexual violence are important enough to prosecute those who commit such acts" and demonstrate to military and militia leaders "that should they fail to prevent or punish subordinates for gender-based crimes, they will be held accountable."

Bemba has not yet entered pleas to three counts of war crimes and two crimes against humanity covering murder, rape and pillaging by his forces.

Moreno Ocampo said Bemba failed in his obligation to "prevent, repress and eventually punish" crimes by his troops.

"On the contrary, we will show how he intentionally avoided any control," the prosecutor said. "Carte blanche was the policy."

Bemba is the most senior political figure of any country in the court's custody. He ruled a large part of Congo during that country's 1998-2002 war, with support from neighboring Uganda. After a peace agreement ended the war, he became one of the country's four vice presidents in a reunited Congo.

He came second in a presidential election in 2006 behind Joseph Kabila. He was elected a senator, but refused to dismantle his militia, leading to clashes with security forces that left at least 300 dead in March 2007. Facing charges of treason, he fled into exile in Portugal and Belgium.

Bemba was arrested in Belgium and transferred to the court in The Hague in July 2008.

Bozize's coup in Central African Republic was successful and he replaced Patasse as president in 2003.

Defense lawyers tried unsuccessfully to have the case dismissed, saying that Bemba had already been investigated for the same offenses in Central African Republic and that his political opponents there and in Congo wanted him sent to The Hague for trial to get him out of the way.