The former Congolese Vice-President, Jean-Pierre Bemba, has appeared at the International Criminal Court (ICC) in The Hague for the first time.
Mr Bemba, who fled the Democratic Republic of Congo last year, was arrested in Belgium in May.
He is accused of atrocities allegedly committed by his forces during a coup attempt six years ago in the Central African Republic.
The former rebel leader has always denied the charges against him.
Correspondents say Mr Bemba appeared at the initial hearing dressed in a dark suit, and waved to his wife in the public gallery as guards led him into the courtroom.
He confirmed that he was born in 1962 and gave his profession as "senator".
He also complained about his conditions.
"The conditions aren't the best, not what I had hoped for," he said.
Mr Bemba went into exile after being accused of high treason in his home country for refusing to disarm his militia after his defeat in presidential elections in 2006.
The successful businessman was one of four vice-presidents in a transitional government in the war-torn African nation between 2003 and 2006.
He was leader of a rebel group, the Movement for the Liberation of Congo, which later became a political party.
In 2002, the former president of the Central African Republic, Ange-Felix Patasse, asked Mr Bemba's group to help put down a coup attempt.
While there, Mr Bemba's forces were accused of widespread rights abuses.
The case comes at a time of crisis for the ICC as the case against another Congolese warlord risks collapse, the BBC's World Affairs correspondent Mark Doyle reports.
On Wednesday, the court ordered the release of Thomas Lubanga, a former militia leader, after judges said he would not be given a fair trial.
A prosecution appeal over his release is due to be heard next week.